I have the SC5100-it has 4 belts. I got mine from Russell Industries. I have had good success, but I can't say my deck meets WF specs, but it runs great and sounds very good.
I did remove the transport to clean and replace. It is possible I could have done it with removing it, but the cleaning would have taken forever. If the Sansui had been my first deck to replace belts, I would have failed. I have learned a lot by doing a few units. Primarily: Take pictures, be patient-walk away when frustrated, go on the assumption that the engineers did intend for belts to be replaced, so look for logical points to remove fasteners to remove the transport. Many decks were designed with removal of the transport being necessary for successful servicing.
Case in point-I began servicing a Teac 3300S R2R, and I could see a small board in the way of where I needed access. It has two screws attaching it to a bracket-just unscrew-right? Well, one was easy-but the other had a tiny nut on the backside of the board, and nothing I could try was allowing me to hold the nut in place while I removed the bolt\screw. Stopped-tried again a day later-nada. Day 3, reasoned that the bracket must be held in place with it's own fasteners-which were below it-on either side of the power cord receptacle on the outside of the case.
I removed screws-bracket out-with the board attached-that's how they designed it-the engineers never intended for that little nut to be removed!