763 wont move in reverse

[mulchman]

starts fine press the green switch hear 2 clicks . makes clunking noise forward but will move , wont go in reverse, arms raise and lower any ideas ? thanks

 

[OldMachinist]

Both sides won't move? Try blocking it up off the ground and try driving one side at a time. Also while it's blocked up try moving the wheels back and forth by hand. It sounds like a chain jumped off a sprocket but I would think it's only one side.

 

[Tazza]

Both sides won't move? Try blocking it up off the ground and try driving one side at a time. Also while it's blocked up try moving the wheels back and forth by hand. It sounds like a chain jumped off a sprocket but I would think it's only one side.

I agree, block it and see if you can turn any wheels by hand, if thy move more than say 5 degrees in either direction it sounds like you have a problem with drive chains or sprockets.
Does the machine feel like its fighting? or can you move the steering levers and the engine doesn't bog down?