Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

@skepyic49,
Sometimes these are not oil cups, but grease cups that are not fully screwed in. Whenever one needs to ad lubricating grease, just screw in the cap a little more to push grease into the eccentric.

I've seen grease cups for all of the Babbitt Bearings on full size hit and miss engines
but have yet to see them on model steam engines.
Perhaps the cups threads are holding it in the center of the eccentrics. Did you try to unscrew the cup
and work the ring off?