i think my stove has the same burn pot as yours. i know the mt vernon insert does from seeing pics here.
i use a long shafted flathead screwdriver to scrape it.
i started with the tool that came w/ the stove. but once i became familiar with my stove, i was able to use the screwdriver and do this job (far more effectively) by feel.
i no longer have to put my head in the stove.
there is never much to scrape. but there is a little carbon scale on the bottom faces usually.
mine has the manual pull cleaning rod. and sometimes i will feel the resistance on that first pull as the stuff is scraped away.
for the inside of my firebox, i use a cheap natural bristle paint brush. 4" wide. like around $2 at the hardware store.
just the plain wooden handle style
(broken image removed)
i have a "shop brush" that i use in the channel that leads to the combustion blower.
but just like a q-tip, i'm careful not to go too far with it (so as not to hit the blades on the blower.)
it looks basically like this. but with a straight handle.
i also use this to finish off the firebox after the paint brush.
the long soft bristles get behind the edges of the pellet chute assembly after the baffle plate is off, better than the paint brush.
i use paper towels with water on the glass and i dry and polish it with a soft non fuzzy flannel rag.