Mine has been warped since the first year of cooking 8 years ago, but keeps getting more twisted. Replaced the controller with an Ortech a couple of years ago and have been very happy with it. Last few cooks monitored with Tappeque have shown some really high spikes after a few hours. Ortech Tech Support sent a new RTD, same results. Looking at the heat shield again, it's raised up 1 1/2 in. or more. Always read that this has no effect on temps, but after replacing it everything back to normal. Temps are + or - 15 degrees.  Could it be too much heat escaping on one side or another, I really don't know.

Could you weld some angel iron braces to the drip pan to straighten and see if that helped the stability of temps?

 I bolted a 10 GA plate to my  drip tray several years back. It's still in use and flat as ever..I used 4, 1/4" stainless nuts and bolts for attachment...   Careful placement of the holes is in order as to assure no interference w/ the heat shield or anything else..... Mild steel, hot rolled sanded or ground clean is what I used... It also adds to the heatsink bank of the pit.

I ran across a guy that had bought a heavy duty one and never used it. After several cooks monitoring with Tappeque, problem solved. Still don't understand it though.

Cool...

I ran across a guy that had bought a heavy duty one and never used it. After several cooks monitoring with Tappeque, problem solved. Still don't understand it though.

A major warp could allow for a higher air flow in the area of the elevated section of the drip tray making for more concentrated heat in that area and upsetting the controllers function.. To replicate using a flat drip tray, prop up a corner and try it.