DJ CD player "Pioneer – CDJ-900" – Plasticizers are apparently evaporating, causing the jog wheels to stick excessively. What can I do?

I have a problem with my DJ CD players. The jog wheel's deceleration rim is apparently made of some kind of hard rubber. After dust had accumulated on it over the years, I tried wiping it with a damp cloth. Now they're sticky like crazy, and my fingers get black when I DJ. The plasticizers…