Good afternoon everyone. I have a Hudson River Stove Works brand Chatham model freestanding pellet stove in my living room. It was installed 4-1/2 years ago. Ever since I started using it this past November, it's been running worse than it used to: - the pellets are not burning as rapidly as they used to. The mountain of pellets in the burn tray piles higher and higher - after about 24 hours of burning, the pile reaches up into the pellet chute and I have to turn the stove off to let the current pile burn back down. - the pellets used to burn down into a fine ash, and the burn tray would be mostly empty. Now the burnt pellets turn into a compacted pile of sticky black ash that turns into an ever-taller brick in the burn tray. Within 24 hours of use, I would need to bang it out of the burn tray so it wouldn't block the starter should I have to turn it off and back on again. - the firebox walls and window now get coated with a thick black soot within several hours, whereas previously it would be a finer, less dark ash that took longer to collect. - after the same amount of use, the ash tray is far less full than it used to be. - a lot more unburnt pellets collect on the firebox floor. - lazier and lazier flame with hours spent burning. I'm concerned because historically I've had real challenges finding anyone who can/will attempt repairs on this stove (established stores with good reputations near me don't service this brand, and the maker/dealer/service company itself in Hudson doesn't want to come to inspect or service it. I couldn't find posts that were obviously relevant to this problem. I am familiar with the "black soot and lazy flame" sticky post. I am using Barefoot brand pellets, the same as I've happily used the last few years. I don't see any obvious vacuum-seal leaks around the firebox or ash pan. I adjust the air intake level to no effect. I have increased the "Combustion Blower" setting which seems to somewhat slow the rate of progress of the problem. I have three semi-un-educated guesses about what the problem may be. Please can someone give me guidance? 1) Some kind of air leak? In the spring of 2018, after I finished using the stove from last winter, I had the stove's annual cleaning done by a company I've never used before (though it's one of the big names in my area). They cleaned it for a couple hours and took it apart and seemed to do a thorough job, but I don't know if it's possible they put something back together poorly. 2) Pellets absorbed moisture? I bought the pellets in May 2018 and had them stored in stacks on pallets in my basement. My basement is usually bone dry but this past year it was damp and even had some standing water due to the exceptionally wet weather all spring/summer/fall. 3) Some kind of electrical/sensor problem? This stove had a sensor go bad twice within its first year of use. Could it be something like that? I'd be very thankful for any advice. Thank you in advance!