I have the above Lawn Tractor Model no 71241. The back wheels have locked up. I took it to a mower repairer they said it was most likely the transmission. Which would cost $3000.00 to fix. The mower has only done 191 hrs but is out of warranty. I have pulled the transmission apart and can't see anything broken etc. It has really got me stumped. hoping you may be able to help. If possible a diagram of the inside of the transmission would be greatly appreciated .Thank you Vince