The compound should be used sparingly, not globbed on. However, if there is an area where the gears aren't in contact, the stuff won't be rubbed off. Rotating the assembly around a few times to catch clean teeth on the pinion will make the pattern more distinct.

Compound left on the pinion is also helpful to observe.

Last edited by CMcAllister; 04/28/22 12:48 PM.
If the results don't match the theory, change the theory.