There's a short, fairly stiff coil spring between the threaded part of the grease cup that screws into the distributor housing and the shaft. There's also a pretty thick Bakelite disc that rides against the shaft to keep the spring from wearing a groove into it. You usually have to dig a little hardened grease out to find the spring. A piece of round Teflon works well as a shaft protector if the disc is worn out or missing.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!