So my belt finally popped! It seems like I have to wind the screw that moves the yoke for the variable width pulley all the way out and then the variable pulley assembly should pull all the way off. Happily it seems to have slid off the end of the splined shaft down into the gearbox. I too have sheared the nylon back gear if anyone has a source. I fear I'll have to reverse engineer it and machine one... It figures I broke the belt an hour after everyone closed for the weekend.