I know its a PITA!!  I bought to in complete liberators on ebay for about 120.00 last year and made a very nice one from both of them and kept the critical parts.  I can't remember exactly but I think I had to pull the cogs and belt bearings off in order to slide them off.  Like any belt they can go bad,  But because they have cogs, I would say if they are having problems, you'll know it alot quicker than a simple slipping belt.