Mine has begun doing that; no "grindy" advance, but the exact same multiple-press behavior on the advance knob around frame 7. It's been that way for some time and doesn't seem to be getting any worse or causing any other problems; after taking one look at a Rollei service manual I decided that any repair at all was way above my pay grade, and I need to get it in to a professional. It's way overdue for a CLA anyway.

If you get yours looked at before I do---which is pretty likely given my usual level of organization---I'll be interested to know what they find.