Ok, my recommendation is as follows:
Step 1: Degrease the motor
I recommend using a product available in automotive parts stores called "Electro-Motive" it is designed to clean electrical parts without leaving a flammable residue. Almost any good degreaser will work (NOT Simple Green or the like)
Step 2: Dry the motor
A hairdryer or small fan works best. otherwise overnight drying.
Step 3: Grease the motor
On both ends where the motors drive shaft stickes out of the motor, add one of two drops of oil for lubrication
Step 4: Watch the motor
Run the motor with no load (belt) if possible for about 3-5 minutes with it being observed for excess heat or smoke.