When I was looking for replacement l-pads/pots for my RSM's, it seemed tweeter replacements in similar size and rating were available.
HOWEVER the mid range ones I found were HUGE, those may be the ones mentioned already.
I ended up buying a couple complete sets of crossovers on ebay, one was for RSM, one was for RS6 I think. I only bought them so I could use the pots if needed in the future.
If you go that route I'm not sure if you should stick strictly with Q series or if other series would work.
Note: I've seen the RSM midrange pots in two styles, both OEM as far as I know.
One is ceramic body with small wire clips holding the halves together, those should be relatively easy to disassemble and clean.
The other style has a metal body with plenty of slots on the back to shoot deoxit into, not sure how easy that type would be to take apart and reassemble.