Hi,
Ive just bought a 220 back to get started on medium format, and im absolutely chuffed with it, but the film advance lever is just a touch wobbley. I read a guy on ebay who's selling a back that the handle on it is really wobbley ("as in it is still attached but I would not like to say it will be for much longer") an he says you can ajust it by screws. Can you? It would be nice to have a 220 and 120 backs for it.
I'm not familiar with the RB backs, but would guess that removing the leatherette disc from the top of the wind-on lever will expose the screw which holds the lever to the winding spindle? A simple tighten may be enough or even a small dab of screw-lock compound to stop it loosening again?