I'm new to playing with the AMNPS also, I'm just east of Stillwater. I think I know what your problem is... You're a Sooner fan.
I didn't try and look back through your previous posts. Are you against a separate box for the pellet tray? I didn't really like the looks of the mailboxes (just me personally, no offense to you guys that have them), so I'm going to do an ammo can. If you go that way you want a S.A.W. 50cal aka the "fat fifty". This is the only one the tray will sit in the bottom with adequate air flow all the way around with the lid on top. Otherwise the door opens sideways and sits on the edge of the lid. Probably a dozen surplus shops in OKC that have them on the shelf.
By going to a separate box you eliminate any "stale air, no draft, starving for O2" issues that MAY be present because all the air coming into the smoker must first come past the pellets. I can't say this is your problem, but you can eliminate the possibility.
I don't know about keeping the tray inside the smoker. Might have to drill holes in it where the tray sits to get air coming in past the pellets. Kinda sketchy though, not telling where all the wiring is in those things. Good luck Okie!
Edit: I read 19 Points as 19 Posts. I'm not telling you anything you don't already know. Sorry.
lol ... hey tjones, you are correct on one thing and that is... I am a Sooner Fan ...
For whatever reason, I was a Sooner fan before I ever moved from KS to TX and then to OK in 1969
I don't want to go to the mailbox thing unless forced to. I am going to try the Tube next time per Todd Johnson's suggestion to me today when I talked to him by Email.....( I will be 79 this month and am hearing impaired, so have to talk by emails and not by phone.) He said to put it on bottom shelf ... back side ... I wrote him back asking if back side or if he meant left side and am awaiting on his reply.
My pellets are stored inside of my house, I do nuke my pellets ... 2 minutes two times and have on occasion tried three times @ 2 minutes per time. Some people never nuke them and claim they have no problems, but based on all of my problems, I am skeptical about those claims.