Paul -
Believe it or not, that belt is not all that unusual. The first signs of wear on a belt in this case is cracks in the 'teeth', and when it wears enough, the teeth or notches come off completely, then the main body of the belt if left in place long enough, separates into several narrower sections.
You don't need to completely remove the gearcase to change the belt, it just needs to be lowered a bit to allow a new belt to be installed. A new 95405 belt has instructions on how to do that. Sounds like your repair master does as well.
As to the noisy motor - In a machine with no belt installed, a good motor will run very quietly. If your motor is noisy or very loud, it will either need to be serviced (looks like a serviceable round motor?) or replaced. There are plenty of U.S. motors around, but I don't know about 50cy. Canadian ones. If you have a good motor to install, the procedure takes about 10 minutes. Between a new belt and replacement or fixed motor, your machine will have a new personality!
Gordon