I have a 2006 9660 sts that I am combining beans with right now and I am having problems getting the rotor to slow down. I am running my rotor about 600 rpms when I start and as the day goes on and I want to slow it down it slows down about 20 rpms the speeds up then slow down and speeds up until it is going as fast as it will go and I can never get it to slow down again until I shut it off and turn it back on then I can slow it down to where I want it until I want to slow it down alittle more then It starts all over again. In the morning if I remember I sit and speed up and slow down the rotor but it still doesn't seem to help. Any ideas? Am I greasing the rotor to much? Not enough? Any ideas are appreciated as it is getting old.