check/replace the fuses on the left lower side of the engine area. standing behind, they're on the lower left and don't look like the every day fuse holders. makes no sense but i had a Z915B and your problem sounds like the one i had and i did/replaced everything you did. i finally went to the...
if you have the part # , search exmark also. they purchased toro in 1998 and most parts are the same with same part numbers. if you've searched for a used toro deck, try searching for a use exmark deck. even a 52" is the same except blades and belt.
go to partstree.com, use your craftsman model # and see if you come up with the same belt. when all else fails, use the dimensions you've been given here and do a belt search on the internet or ebay, just longer as you determine.
see if it tries start easy on a squirt of starting fluid. that will help determine if it's a fire or fuel issue. if it fires immediately, sounds like a fuel thing. is there an inline fuel filter? pull the fuel line before the carb to see if you have a full/stead flow. that one may have a fuel...
i have 2 Z915B zero turns and they have worked fine until now. one has developed an issue that has me stumped. i hit the ignition switch to start and there is a faint click and a louder buzz but won't crank, turn over. nothing. nor does the hour meter show. the click/buzz sounds like it's coming...