Confession: I’ve been using a Behmor 1600 for the past year in favor of my bread machine roaster. The primary reason was that my heat gun caught on fire, but I also wanted a drum roaster that was quiet and would let me see the beans.
So I’ve been using it for a year and have been keeping the interior walls clean like the instructions say to do. However in the past month my roasts have been taking a long time, 10oz of beans pushing even the boundaries of the 1# setting. Flipping through the manual alerted to cleaning the inside of the machine as well, and I found the cause of my problems.
I cleaned out the dust & lint with my vacuum’s angled attachment and roast times went back to normal. My best guess is that because it was not able to draw enough air to keep the electronics cool so the roaster lessened its heat output as to not cook itself to death.
A word of advice though, after you get the side panel off plug the roaster back in before vacuuming it out in order to ground it and to dissipate any static electricity buildup. Otherwise you may fry the circuit board as vacuums generate a lot of static. Just be careful about poking your fingers in there!