Our '99 model 2388 gave us trouble with this for years and years. I was told it was not unusual and just required regular maintenance/cleaning/greasing.
We would wire brush the exposed threaded area clean (also tried a lanolin lube spray or leaving it dry and clean), wind the speed up to max, grease it with 2-3 pumps, then wind it down to minimum grease it there, wind it up flat out, back it down to the working position and another 2 shots there. This was done weekly to try to keep the sleeve clean and greased, but it was often difficult to get it to move that far. We would have to stop the rotor and help it along with a wrench if it stalled. Very frustrating and time consuming.
We also tried cleaning the electrical terminals and testing the amperage.
Over the last couple of years it seemed to get worse and we also had some trouble with the cleaning fan vari-speed as well.
Last year it got to the point where it wouldn't move the chain more than enough to take up the slack. Our mechanic said they had never heard of one of the electric motors siezing up/burning out so it must be the threaded adjuster that was siezed with dirt/chaff etc. We dismantled the whole thing, cleaned it out, lubricated everything and put it back together again. Still no better, so we took the chain off and found that the electric motor could barely turn over with no load at all. I wish we had tried this sooner!
By the time a new electric motor arrived the harvest was done.
It may be worth swapping the electric motor on the cleaning fan over to the rotor to test if the motor is slowly loosing its torque, as it seemed to take years for ours to finally give up.
