I got this tractor from a friends Dad for free. I got it started just by getting a new battery and cleaning the carb. I am not familiar with these engines or tractors. I did try searching this site for the problem but if it does exist I didn't ask the question right. Wouldn't be the first time. I had to put a new tension spring on the mower and I replaced both the belts. Got everything running and was looking forward to trying it all out. I pulled the tractor out, stopped, engaged the mower and then the tractor would no longer move. I disengaged the mower and it still wouldn't move. Turned the tractor off and restarted then it would move as long as the mower wasn't engaged. While waiting for the mower parts I was driving the tractor around and it seemed to have a similar issue when it just stopped moving. Turning off and turning it back on got it moving and I could not recreate the issue again. The mower issue recreates on demand. I checked the oil level in the hydraulics appears to be correct. Not sure what to check after that. Any help would be greatly appreciated.