Is this safe to do?

Im half way through changing my timing belt and a couple of the idlers have rubber residue from the the belt ive removed.

Would it be reasonable to take them off and polish them up with a bit of very fine wet and dry paper?

Also, is there any way to spot an original timing belt compared to a genuine subaru replacement? (if that makes sense)

Thanks!

 

Fine wet n dry or a wire wheel/brush will do the job - OEM belts are clearly marked with Subaru on them.

Mick

 

can just about make out subaru logo on it, guess prev owner might have bought genuine though