Yes there are two plates that cover the hear exchanger.I would go back in and clean the heat exchanger baffles thoroughly. That's the most critical point of your furnace's heating efficiency. The manual has instructions for removing the plate that covers them. The manual recommends doing a cleaning once a month; I'd probably be in there every other week.
As the manual states: "Keep in mind that the cleaner the heat exchanger surface is kept, the higher the heat transfer efficiency will be."
When I bought the house there was so much ash build up the chains couldn't even move.
Took me several hours to clean to thoroughly the first time.
Older couple used to live in house and had oil furnace serviced annually and never had the pellet furnace cleaned/serviced. I actually was able to talk to tech who installed it for then in 2009. So I think/assume they never really used it as the pellets need to be brought a long to get to basement. It does have a silo and auger that fills the hopper automatically.
Easy to clean front of heat exchange but harder to clean the back of it. I'll have to investigate that a bit more and clean now regularly I think.