Sparhawks:

Yes, you explained a "Bendix" but MB uses a solenoid to engage the pinion gear into the ring gear. But you could be right about the grease on the shaft that the pinion gear slides on.
The only absolutely reliable starter drives are the old style ones where with your foot you pushed a rod that slid the starter pinion gear into the ring gear but they went out of style about 1940.

P E H