I have a mtd mower model 13w27752031 was doing fine parked it when I went to use it again motor cranked fine
but tractor would not move there seems to be a lot of slack in belt pulled belt off and it does not appear to be worn
2 things you might chk:
1) verify park brake mechanism is not frozen up (located on side of tranny case) (loosen with several shots of rattlecan brake pad cleaner)
2) with good drive belt installed (no excessive slack), make sure that driven input pulley into tranny is not turning by itself on input shaft due to damaged shaft splines...
What happens is that the variable speed pulley has not shifted back so that there is tension on the front belt. The remedy is to put the shifter into neutral, and increase the ground speed to the fastest position while the engine is running. This will reset the pulley and you can now put it into forward and reverse and go. If still a no go, my guess is that the rear belt is off which is accessible if you remove the battery.