Maybe it's not a consideration, but will the Permatex "glue" the fan to the pit making it difficult to replace?

Perhaps you could put waxed paper on the pit then run the Permatex bead on the fan and bolt it in place.  When the Permatex is set up (and "glued" to the fan), remove the fan and discard the waxed paper.  That might leave an exact gasket on the fan.

The gasket goes between the fan housing and the pit body.  The fan mounts to the fan housing so there is no worry there. A silicone seal/gasket is for the most part easily undone.. The bad part is removing the silicone material from the sealing surfaces . 

Soot caused by a burnt out combustion fan gasket was discussed  at length on the  "old other" pellet site years ago. I cant remember "why" it causes soot, I just remember that id "does". I seem to remember that GMG recommended replacing the gasket for soot as well.

When mine started have the same issue I checked the gasket and sure enough it was burnt out, and I mean burnt to a black crisp. Very little of it was left. I replaced the gasket using the red hi temp silicone and that solved the problem for a few more years.  Now I am getting soot again so I figure it is probably the same thing. This time I want to leave out the gasket and just use the copper Hi temp gasket maker. I think it will last longer this way.

I think the fan gasket gets damaged when you run the grill at 450 - 500.   

Soot caused by a burnt out combustion fan gasket was discussed  at length on the  "old other" pellet site years ago. I cant remember "why" it causes soot, I just remember that id "does". I seem to remember that GMG recommended replacing the gasket for soot as well.

When mine started have the same issue I checked the gasket and sure enough it was burnt out, and I mean burnt to a black crisp. Very little of it was left. I replaced the gasket using the red hi temp silicone and that solved the problem for a few more years.  Now I am getting soot again so I figure it is probably the same thing. This time I want to leave out the gasket and just use the copper Hi temp gasket maker. I think it will last longer this way.

I think the fan gasket gets damaged when you run the grill at 450 - 500.

I've had my DB for 5 years now and had the wiring get burned. That was due to a faulty controller that said 800 on it. GMG sent me a new harness but I have still used the same one.  I don't do a lot of cooks at 450-500 so I was wondering how many cooks have you done at those temps? Thanks for you info! Some things to remember.

I used to do quite a few chickens at 450 to get crispy skin. It was greasy and messy but it worked well. after the gasket burnt out and I replaced it, I decided not to do any more cooks over 350F.  Now I find out that my wife has been cooking at 400 plus with it. I guess she didn't get the memo.  

I figure that might be why I am having problems again. 

Maybe it's not a consideration, but will the Permatex "glue" the fan to the pit making it difficult to replace?

Perhaps you could put waxed paper on the pit then run the Permatex bead on the fan and bolt it in place.  When the Permatex is set up (and "glued" to the fan), remove the fan and discard the waxed paper.  That might leave an exact gasket on the fan.

Another possibility would be to wipe down the mating surface with silicone oil prior to putting the fan and Permatex on. That 'should' allow for easy removal, and also the need to remove the wax paper as silicone oil should be good to around 475 degrees.

UPDATE:

I took the combustion fan housing off this weekend and sure enough, the gasket was burnt and in pieces.  If I wasn't clear before, this is the gasket were the fan housing connects to the bottom of the grill.  (See picture below) It's a two person job. You need one person on top to hold a wrench on the bolt head and another person underneath to ratchet off the nuts. As you can see in the attached picture, there are 6 bolts to remove.



I removed the old gasket and sealer, l cleaned and wire brushed the surfaces and reassembled using the  Permatex Ultra Copper only. Let it cure for 24 hours then cooked a spatchcock chicken to test it out.

Worked great! NO MORE SOOT!!! 

I't is my hope that this is a  permanent fix.

 That (Permatex Copper) should be the end of your gasket burning problem.. Just makes me wonder; why wouldn't GMG either go with a high temp silicone seal or a more heat resistant gasket?  This seems to
 
 be an on going  problem that if corrected would rate their pits one increment higher on the reliability scale.  Part of the answer is "up front " cost. The pay-back could far offset the minuscule cost in future pit
 
 sales.

The new GMG Prime and Prime plus grills don't have a combustion fan under the firebox. They now have one fan under the hopper that pushes air from the hopper to the firebox in a chamber similar to furnace duct work. Still have airflow to firebox like before, just one fan instead of two. One under the hopper and one under the firebox.

The new GMG Prime and Prime plus grills don't have a combustion fan under the firebox. They now have one fan under the hopper that pushes air from the hopper to the firebox in a chamber similar to furnace duct work. Still have airflow to firebox like before, just one fan instead of two. One under the hopper and one under the firebox.

Interesting.

I've decided not to upgrade to Prime. I'm just going to keep refreshing mine every year or two and replace parts as needed. Thats one of the nice things about GMG.  You can buy and replace every part if need be.

The new GMG Prime and Prime plus grills don't have a combustion fan under the firebox. They now have one fan under the hopper that pushes air from the hopper to the firebox in a chamber similar to furnace duct work. Still have airflow to firebox like before, just one fan instead of two. One under the hopper and one under the firebox.

Do the Choice Grills have the just one one fan under the hopper too?