farmertim On our 2388 is was the back thrust bearing on the adjustable rotor drive pulley. It's the one that fits on the back of the adjustable colar and rides on the front half of the drive pulley. These things are notorious for starting fires, because when they go out, they sling buring grease all down on the elevators. They also ruin the front half of the pulley. luckily, we didn't have any dust in the engine compartment or underneath the pulleys to get going, just on top of the elevators and some braces. For dust fires, the best thing I've seen is to carry a pump up hand sprayer full of water. A fire extinguisher will blow the burning dust around, while the garden sprayer will put out a small amount of water at low pressure to wet things down. We got this idea from a neighbor whose 8820 would catch on fire almost everyday!!!