I just got a Leicavit (black) for about $880 boxed and mint. Tried it on my MP with a tester roll of film and when I advance quickly (like they say - "advanced photogs... 2 shots a second..." ), every few advances it feels like it slips the advance or doesn't fully advance. The anomaly starts in the last third of the range of the advance.
I also have another Leicavit (silver) that is basically in the same condition. Bought it from a guy that actually never used it. I thought i'd compare the black one to the silver one under the same conditions (same camera, same roll of film, rerolled back into the cannister). With the silver one I can fire through the whole roll as fast as I can and no "slipping".
I'm not sure that that's what it is - slipping. On the silver, the pressure is constant throughout the whole advance range of motion. With the black one, if I'm going relatively slow and controlled the resistance of advancing disappears in that last third or quarter of the range of motion every 4th/5th advance. If I go much faster to rattle through the roll of film, its much more common, maybe every advance or every second advance. This doesn't happen on the silver one.
I compared the "inside" of the leicavits, the side that mates with the bottom of the camera . The nodule with the jagged triangle protrusions that drives the advance looks exactly the same on both, no visible damage or wear at all. It isn't rigid but can move around a little within its "fitting". That's the same on both. The wheel that sits over the film spool moves the same on both.
Since I'm using the same roll of film and the same camera, and there is no obvious difference, I really don't know what's wrong. I'd really rather not give back the lecavit since it was a little cheaper than the usual sale price and also a local sale in person. Any ideas/ suggestions? Anyone have the same experience?