The RIMAC company made a tool for installing and removing the press in grease fittings for the Model A. It was #21 and called a "Nok-In-Out". Has anyone seen one or have one I could get a picture of?
I am guessing that the RIMAC Tool tool is placed against a press-in grease fitting and then hit with a separate hammer. Doing so would avoid damaging a grease fitting from an errant-placed blow with the RIMAC Tool.
My Avatar photo has that tool pictured. It was made by Rinck-McKilwaine of New York. You can usually find them hunting on EBay for Rimac tool or nail puller.