i had to replace the fan speed adjustment motor on our 1660 last fall. finished summer combining and went to do soybeans and had no fan adjustment. that could be a possibility.
At first of season, I'll have no fan speed up or down unless the connector at the motor is pulled, cleaned with lectroMotive spray, airhosed and then reconnected. Works every time thereafter. Haven't had issues in the rotor dept. as yet.
