Okay, so I've searched and can't find anything about a seal for the endplate on the engine block. Is there even a seal there? I was told that the engine needs one to run. I hadn't heard of it before so I thought I'd ask.

 

When you are referring to a seal on the endplate, are you referring to a main seal on the eccentric shaft or the side/corner seals on the rotor? The seals that touch the end housings are the oil control rings (2), side seals, corner seals, and the ends of the apex seals on one rotor. There are the water seals between the end plates and the rotor housings and there is a main seal at each end of the eccentric shaft. One is pressed in the rear stationary gear and the other is installed on the front cover. If the one you are referring to isn't there then I don't know what it is.