Travis Lopi AGP insert problem, shutting down on T-Stat

looking for ideas on diagnosing this

AGP insert, . I have it set up with a millivolt programmable T-stat and it has been working flawlessly since Nov 2014 (installed stove 4/14), Yesterday it started as usual in the morning and then shut down shortly after the fire started, it went out of T-stat mode, I pressed stop, and then restarted T-stat mode and it ran perfectly all day yesterday. Went to bed last night and the same happened this morning, except three attempted restarts all failed, the stove starts, flame is produced and then it shuts down and goes out of T-Stat mode, the red Stop light does not come on, I am assuming the start itself failed. . Any ideas where I should look to address this issue? Could it be a snap disk or bad door gasket?

Thanks for any help you may be able to give me in figuring out how to deal with this.

seems at this point it was a door gasket issue, the door gasket was fraying and falling apart in the area where the two cut ends meet, I think that is why it would fire up but then shut down during the proof of fire phase, bad vacuum. I squished it in such a way as to ensure it was sealing when the door closed. It ran without a problem on the t-stat for 2 full days, 4 different time\settings\ 3 start 4 stops @ day, so today I replaced the door gasket entirely .. what a pain in the ass to get the old silicone sealent out of the groove used a 3/8 " conical grinding bit in a drill followed by a wire brush bit in the drill had it fired up on manual now for the last 2 hours and it seems to be fine, will switch back over to t-stat mode in a little while after I shut it down and let the 4:45 pm start cycle on its own.

btw any tips ( this is my first season etc) on how to cut the gasket rope so that the edges of the ends dont fray and unravel ?

thanks for the suggestions

that's a good suggestion .. and yeah avoid messing with it if at all possible.. took an hour to grind out the old sealant with a drill and grinder bit down to bare metal to put the new one in.. I'm guessing high temp metallic duct tape is what you have there