A heads up for fellow GMG owners, this is somewhat common knowledge if you do a fair bit of digging, but I wanted to share in case anyone ran into the same issue.
My Jim Bowie I got for father's day in 2016, and it ended up being right around when they were offering the stainless steel first gen 1 piece heat shield and two piece drip pan. This heat shield had a notch that did not allow the heat shield to move, and the V for the heat diffuser underneath was not in the middle like their newest version, but all on one side.
I ended up modding mine by notching out an additional 7/8" on the auger side, which made my temps SOLID when low and slow cooking, but really bad when cooking burgers at high temps.
I called GMG yesterday, and they're sending me out a replacement heat shield at no cost. The lady that I spoke with said that it was the second one she had replaced in a two hour period, and that they've identified this as a design issue.
So, if you have one of the first gen one-piece SS heat shields, call GMG and they'll take care of you! I am really impressed with their customer service. They even threw in a rub for my troubles.
Now that pelletheads is gone, I was only able to research using google cached pages, so glad to get another good forum up to share this info, and hope it helps someone avoid the headaches I've been going through trying to dial in my jim bowie across all temp ranges.
*Edited to clarify the heat shield type as first-gen one-piece stainless steel