It's years since I've hand an RX50 apart (I could be convinced to strip one to chekc if need be), but it's likely to be a fairly hard felt. That's what most single-head drives used. The good news is that this pad only touchss the no-regoeded side of the disk. On the other hand, it might transfoer grot to the head if the drive dorr is closed with no disk in place. and it may contaminate the back side of hte disk, which then contaminates the other head if you put the disk i na double-head drive (e.g. the one on your PC that you used to transfer data to/from trom RX50 disks). At one time, for some drives, this pad was actually a field-replaceable part. I don;t know abotu the RX50, but replacign the pad is one of the few filed repairs that HP recomemdeed on the single-head Sony 3.5" drive used in the HP9121, etc. can be fone. Basically, remvoe the screening can, then the 2 side frames, unplug all the leads from the rear PCB, remove that PCB, remvoe the front casting, then remove each disk clamp arm (do not loose the C-springs). Tkje off the remaing 2 PCBs (R/W and motor cotnrol). I would nto dismantle the head carriage assembly unless you want a fun job of realigning the thing. At this point it should be fairly easy to sse these felt pads. Try cleaing them with propan-2-ol. If they will nt ocome clean, I wonder fi some suitable material could eb foudn to repalce them. My first sugggggestion (if you cna get it) is the sort of hard felt used in some musical instruemnts. -tony