[Arran]

On the G.E they used Telechron clock motors that had the rotor and primary gear reduction inside a copper coloured capsule mounted in a hole in the iron. After 40+ years the oil usually dries up and the rotor stops working, I can't recall what oil to use but I think it was something like sewing machine oil, 3 in 1 oil, or electric motor oil, and the way to get it into the capsule is to remove the rotor assembly from the clock, heat it up, and to feed the new oil in around where the little pinion gear sticks out. Here is one web page showing the technique:

http://www.prepostmodern.com/rotors/

More on Telechron clocks:

http://www.telechron.net/main.htm

Regards
Arran