mtd transmission works in reverse but not forward
MTD 46" model 13AN771H729 (2007)
drives ok in reverse only. Won't move in forward and grinding noise coming from gear box. Removed gear box and dismantled. All looks ok, seems fine on the bench but when reinstalled same thing.. Also checked linkage to make sure it was going all the way into forward. Not sure if problem is with the differencial, gears or slide. When I turn the drive pully by hand on the bench and shifted between neutral, forward and reverse it looked fine. Trying to decide what parts to replace, gears, differential or what.
Anyone have any ideas? Thanks