I did take the fitting off and dig around; there was nothing else in there.
From threads I've read elsewhere on this site, the grease cup and spring/button are the original method. One would have to grease the cup every 5k miles or so, and the spring/button would press against the grease. Apparently, some would take those items out, and install a zirc fitting, relying on the ball valve to maintain grease pressure when filled from a grease gun. Not sure if this was done because the cap was lost, or they didn't want to keep refilling the cup.
Of course, grease guns seldom contain the correct type of grease for this application. I have a gun with actual cup grease...hit-and-miss engines frequently use this same lubrication method.
The nylon part is available at Lowes; I can 3D print in delrin to make any part I need.
All good info.
Thanks!
-Kevin
