Hey Dave, I believe they decided that after many replacements that just warped again.  For what it has cost them in replacements, they could have made them out of heavier gauge SS for a few bucks?  Not complaining really since most other brands do the same.  The Blaz"n was a round, cupped, 3/16" SS.  It did not warp, but because of its shape and support arms, it arced the fire downward and caused the hot spots that peeled the paint off the bottom-underneath.

Not sure I will keep the mod.  Want to make sure I can live with the slower rising temp and even slower declining temp. I can resolve the clicking by loosening the bolts by a turn, the soot and such will keep them from turning loose otherwise OR can use another nut and lock washer to position them. The higher actual temp on hot cooks is no big deal as I can adjust the set temp if necessary. At smoking temp of 225* it is right on. RT is right about one thing IMO, the warp was no problem other than it irritated me from an OCD standpoint. Like having a nice new car with 3 black tires and one red tire.  Plan to play with it a while longer.   

Curious how it took longer to come to temp or come down. The flame and heat would just come out the sides I would think. The flame isn't enclosed. Hard to imagine that piece of SS changing much. What do I know, you have the test data.

 One would think if people called in now and complained of the warpage, they would offer to sell them one of the new cast iron ones.

Curious how it took longer to come to temp or come down. The flame and heat would just come out the sides I would think. The flame isn't enclosed. Hard to imagine that piece of SS changing much. What do I know, you have the test data.

 One would think if people called in now and complained of the warpage, they would offer to sell them one of the new cast iron ones.

Fire pot is like a blow torch, it turns the metal plate into a heat sink. The thicker the plate the more heat it stores.  Ought to make it more efficient, and the PID should adjust as needed to keep the temp at what you order. Unfortunately, the bigger the heat sink the longer it takes to heat up or lose heat. So if you overshoot with your initial requested temp, it takes longer to compensate and you are overcooking while waiting for it to adjust and visa versa. That PID has been programmed to interact with the factory characteristics of this grill, including the time it takes to heat up all the inner parts to a steady temp as ordered and also the time it takes to go to a lower temp or higher one. I am not sure how sensitive all that is, so I am going to test all that out before committing long term. If the delays are inconvenient, or if the temps are unstable compared to original then I will consider laser cutting out a large central portion of the 3/16" plate, maybe a 6" circle. That will reduce the mass of the "heat sink" hopefully enough that the effects on temps etc. will be reduced so as to be insignificant. Meanwhile the remaining plate should still be rigid enough to block the warp.  I'm an unemployed 86 y/o with nothing better to do.. 

I suspect that the new diffuser is not offered because it installs differently?  Don't know that, but who wants cast iron in their nice SS interior anyhow?

Spent most of this cold, gray day testing and adjusting. After loosening the nuts and locking with lock washer and extra nut, I cranked up the 590 set at 225*. Placed two temp sensors, one on left-central, one right central. After reaching the temp and 30 minutes to stabilize, the control read 225* and the left center was 217*, the right center 235*.  I switched the sensors to make sure they were both accurate and got essentially the same readings. (left 216-; right 239*). Then for final, I placed both sensors in the center/central position, and they were identical at 230*. So I went into "Offset" while the machine was running and added 1+ unit. After about 20 minutes they both read 225+-one or two, while the control sensor read 225*. Best I have ever gotten a match. I think the reason that the left central reads colder is because the fan blows from left to right and the flow favors the fire pot holes on the left and center as compared to the holes on the right. ? Not sure of that logic but seems reasonable to me. I have an old solution for evening out the heat from the diffuser--cut out the side slots an extra half inch on one side only, and then tweak it a little to the right so that more heat escapes on the left side of the diffuser.  I did this on my old Traeger with excellent balance on both sides of the grates. Does not take much offset to get a better distribution of the heat. There were no clicking noises! And after satisfaction at 225* I kicked it up to 400* with both extra sensors still in the middle and they both read 417-420. No big deal:at that temp. So I added my portable griddle and grilled salmon for dinner.  It was wonderful, with fries in the air fryer, and left over cranberry sauce. I noted that the cool down was not delayed in an obvious way, so declared the mod a success.  Will keep it as it was at the end of the day. Thanks for all the input. 

Great  to hear it is working and you are getting temps to where you want. I think GMG diffuser gets slid one way or the other to help with evening temps.

 I messed with temps when I first bought the RT and it irritated me as they were not very close at times side to side. It was nothing to see 50 degrees right to left. When I bought the GMG I decided no need to be messing with temps. Just cook, I know it cooks a little hotter than set temp.

Great  to hear it is working and you are getting temps to where you want. I think GMG diffuser gets slid one way or the other to help with evening temps.

 I messed with temps when I first bought the RT and it irritated me as they were not very close at times side to side. It was nothing to see 50 degrees right to left. When I bought the GMG I decided no need to be messing with temps. Just cook, I know it cooks a little hotter than set temp.

If I was unaware of the warp, no doubt I would not have suspected any problem and would have been cookin instead of lookin. But because of who I am, I would be more likely to go to bed and not sleep well, maybe think up a solution, get up at 2AM and go out and fix it.

 Striving for perfection is a sickness I suffer from as well.. 

 Thanks for the update okie.

 Striving for perfection is a sickness I suffer from as well.. 

 Thanks for the update okie.

So are we "special" or just "mentally ill" (in the context of today's society)?

 Striving for perfection is a sickness I suffer from as well.. 

 Thanks for the update okie.

So are we "special" or just "mentally ill" (in the context of today's society)?

I like to think "old school".  That is, we learn how things work and repair with pride.

 Striving for perfection is a sickness I suffer from as well.. 

 Thanks for the update okie.

So are we "special" or just "mentally ill" (in the context of today's society)?

I like to think "old school".  That is, we learn how things work and repair with pride.

I used to "repair" computers.  Remove the bad component (transistor, capacitor, etc.) and solder in a new one.
Now it's replace the whole thing.

Spent yesterday afternoon and night adjusting and testing with the mod and without it.  Was worried that the time delay getting to temps would be irritating. But that was minor compared to benefits. First tested temps on left center, mid-center, and right center first without the  mod and then with.  Strange and surprising results. Using fresh LJ Hickory Blend.
First test at 225* set and without mod: The diffuser was warped about 1/2". Offset adjusted to +4 to get 225* actual temp.  Left was  205*, center 225-227* and right was 241*. Not happy with sides. With set temp to 275*, I got L 261*, C 278*, R 301*.  The above are all after letting the pit adjust for 30 minutes.

Second test with Mod included and at 225*:  Had to adjust the Offset to +6 to get center temp to 225*+_ 2, Left 210*; Center 225*+_ 2; Right 236*. With temp set at 275*:  L 258*; C 278*; R 304*. 

Not a big difference. The real problem is the difference between left and right. I have made the notch in the center of the diffuser sides about 3/8" bigger on one end but saw no significant difference. Might make it bigger, but I have another idea. BUT will try it first before describing. Stay tuned.
 

New idea:  Okay I was thinking about why we call the diffuser, "diffuser," or "deflector".  Well it does both, but we use it mostly as a diffuser--as it diffuses the fire and heat equally in all directions.  I think of a deflector as shifting the heat in a specific direction. In order to do deflecting I would think you would have to tilt the deflector to increase flow in the direction desired. I have never seen any description of doing so.
Problem:  MY 590 (and others I have read about) is cooler on the left side than either the center or right side:

With Mod and set at 225*, I get the following temps,  Left Center 205*  Center 227*  Right Center 241-246*

So I lowered the right side of the Mod Plate by 1/4" by placing a nut between the plate and the deflector/diffuser at both right bolts. (no pics, sorry) which gives me a tilt that deflects more to the left side.

Result with deflection:  Left Center 224-225*; Center 225*; Right Center 247.  It took an some extra time to settle but was very stable at the endpoint. Almost unbelievable result, but it happens.

Impression:  Makes sense and it worked, BUT had no apparent effect on the high right side. My diffuser/deflector was centered. 

Question: What  could make the right side significantly hotter than the left or center? 
Answe?r:Drip pan is tilted downward to drain, and is significantly closer to the deflector on the right as it goes by, thus R drip pan is exposed to more direct heat and flame as it exits the d/d. Obviously the SS Mod plate lowered on that right side by 1/4" made little difference since the whole d/d is not lowered there.?? My assumption is that the drip pan is hotter in that spot and radiates that heat upward. Will look at the bottom of drip pan for any evidence.

What else could be done to lower temp on the right? Not sure anything is needed but to just know that and work around it or use it as needed.
Comment: I know that if I never knew there was a difference in grill temps from side to side, I would probably continue cooking great meals on this fine grill. I also know that this is not uncommon in most pellet grills on the market although the hot side is not always on the right.

Plan: Since I am old and unemployed, I will do a little more sleuthing before giving up on the right, but am very happy with the results to date and feel I have discovered new territory that might be worth a little research by the manufacturers to alter their rather rigid design concepts for diffuser/defectors (like adding little "tilt" where needed). Or maybe conclusions might include "Live with it! Its no big deal"

I think the key take-away is that you know what the variances in temp are, and you can adjust your cooking accordingly.

I have not tested the Memphis I have, but would expect temps on both sides to be very close as the drip tray (flavorizer as Memphis calls it) slopes in both directions.
The center would be hottest since it is directly over the burn pot and there is no diffuser above the burn pot.

I think the key take-away is that you know what the variances in temp are, and you can adjust your cooking accordingly.

I have not tested the Memphis I have, but would expect temps on both sides to be very close as the drip tray (flavorizer as Memphis calls it) slopes in both directions.
The center would be hottest since it is directly over the burn pot and there is no diffuser above the burn pot.

I agree. If you check, let us know. I pulled the drip pan and the picture confirms in my mind that indeed more heat is absorbed by the R dp as suspected. More soot and ashes on the right of the dp and clearly where it exits the diffuser.  Now, what to do?? Not sure anything since lowering the d/d might diminish the direct effect on the drip pan, but would place the d/d closer to the fire pot, and perhaps it would gather more heat as compared to the left side of d/d itself. Think I will take what I've gotten and stop there for now. Pic of underside of drip pan speaks for itself.

After all the above I was concerned about the size and weight of the SS plate. So I ordered a 1/8"" 304 SS 9" x 9" plate to replace the 3/16" 9"x 9".  I applied it to the diffuser/deflector in the same manner with the right side lowered by 1/4" as before (assuming it would deflect more heat to the cooler left side as before but without as much heat sink effect).
1.  After repeated tests at 500+*, the d/d did not warp. So IMO 1/8" thickness is enough to control and prevent.
2.  With separate tests at 225* setting there was only about -8* on left and +13* on the right sides with the usual variations over time.
I believe the mod can be done with 1/8" steel as effectively as with 3/16" or 1/4" to prevent or correct warping.
Thanks for all the input.  Appreciated.