Originally Posted by ArchaicArcane

Please don't put lubricant or oil in with the motor brushes! This is a fast way to spoil your motor.
Lube or grease goes in the grease tubes - to lube bearings or bushings - which are close to the brushes - which transfer electricity to the motor's inner workings - but are not the same thing! The manual will help you distinguish between the two.

Oil goes where metal rubs on metal. Lube goes on gears - G for G. Grease for gears. The reason we do this is to avoid having the friction reducer - oil or grease - fling off and not protect the gears.

With the advanced age of these machines, it's best to remove covers and plates and oil the metal on metal spots rather than just dripping oil into the holes. This is because when these machines were designed it was assumed that they would go in for service from time to time and that's where the technician would remove the covers and plates and oil the metal on metal spots. Now that few if any go in for service, owners should take on the responsibilities of the technician as well.