I'm getting clinkers in my burn pot all of a sudden

[Dr.kittens]

I am getting clinkers in my burn pot all of a sudden, and about a half to one handful of pellets are going unburned. I'm using the same pellets (wood & sons) and the same air flow (totally open) that It was last year. Last December I neglected my cleaning duties for a couple weeks which resulted in a nasty hopper fire. I don't know if that's related to the cause, after effect, or coincidence but it's concerning me that I have such a large build up in the burn pot. I clean it diligently, at least one a week now, but I know this still shouldn't be happening. if anybody else has had this problem and knows the solution I could really use some advice.

 

[Mt Bob]

make and model of stove.

 

[Dr.kittens]

make and model of stove.

Breckwell P2000i