Hi Dirk,
Yes, I did run into problems with the door hinge grease fittings on my 66 230SL. Because they had a hex, I assumed that they were screwed in. After three of mine broke and looked exactly like yours, with a little knob on the back side and nothing in the hole, realized they weren't going to unscrew. I assumed that after 50 years, they had welded themselves into the holes and that what i was seeing was a tiny hole in the fitting and a larger hole in the part of the fitting that broke off in the hole. I never really figured it out so I ordered some fittings from the local dealer. (A 000 997 04 88).
Now here is the frustrating part. When I was in engineering in the US auto industry, if I had done what Mercedes did, I would have been fired instantly. Part numbers and part design history are sacred. The parts I got from the Mercedes dealer, ordered from Stuttgart, were the same part number as the original parts according to the EPC, but the parts are completely different. They have no hex and they are press-in parts. Somebody changed the design without changing the number. My original ones were like yours. The photo is of the MB replacements (same part number).
My solution was to measure the fitting diameter, drill a slightly smaller fitting hole in the hinge barrel, file the hole to a press fit (a few hours work for three fittings), flush out the hinge pin hole and hammer the fitting into the fitting hole. I greased the three new ones and managed to get the original fourth one freed up enough to grease it as well.
The whole thing was a royal pain.
Good luck.
Tom Kizer
