SME's can easily be stripped out for service, although the cueing assembly is a pain to remove (on later arms at least). Once stripped and cleaned out, I'm sure SME or Rega would/could supply a phial of fresh silicone damping fluid to re-charge the piston.
As for swivelling headshells, a bodge could be to get some stud-lock type liquid (the green stuff used to lock tape head setting screws amongst other things) or similar. A drop or three of this around the headshell socket will stay tacky long enough to set correctly and then, if left for a few hours, should all but glue it in this position, not tightly, but enough to firmly hold the shell in correct azimuth. I'm sure though, that there are still people at SME who could advise on a correct course of action and they might even have some parts left!
Tear down these walls; Cut the ties that held me
Crying out at the top of my voice; Tell me now if you can hear me