My old S950 went exactly the same way.....in the end I fitted 3 new drives in it. The only way to be sure to get a drive that worked was to get them out of other S950s ! I even ended up buying a whole new s/h 950 just for the drive in the end !
its been a rather epic 8 months since I bought it... been getting regular use as a trigger to midi (and a disk drive fitting practice machine), real nice to have it working now: if this didnt work out I was going to have a little drum machine sale to fund the vermona drm1... in reality the s900 is more what I want and will play nicely with the rest of what I have. Going to spend tonight sampling the modular ready for a percussion fest tomorrow.
funny the stuff you miss: i still look out for quasimidi 309's despite not liking the interface much