I've some problem (jams/ skew) with separation rollers of PF601 (paper tray4 - 5), I heard that some new rollers are available (the rubber should be red !) and also a new system (modification to add) to the separation roller mechanism in order to increase the weight for separation.
There are currently 3 types of rollers available for PF-601. The standard grey the newer style (tyres are ribbed)
A03XR70900 PAPER SEPARATOR ASSY
A03XR71000 PICK UP ASSY
And urethane rollers that are actually used in the BZ1050 for coated stock option. These are the orange/red ones you are talking about. You will need the above kit to fit these.
However we don't have too many problems with jamming from PF-601, what kind of jams do you get?
I've no specifique problem with separation, but mainly skew with papaer coated, some technicians tell me that there are new roller for that ! ( red ones!) that's why I ask you.
PF-601 Skew - release the feet nearest to the engine so the PF is now "hanging" off the the engine. Try and print - Skew gone? Then lower feet to just take the weight. Skew not gone? Raise the rear foot nearest the engine and print test chart 16 at every half or quarter turn and see if it gets better. This usually works for me.
C6500 New separation roller and device PF601 
Linear Mode
