That might work - although I've never tried it. I mentioned Liquid tape in the other thread - it worked for me, and is available everywhere. If you want to avoid spending money, I can relate - the thread below mentions silicone rubber as a possible coating to restore grip to an idler:
http://cr4.globalspec.com/thread/21396
There are some other ideas, all related to softening/restoring grip.
Cheers,