I blew a hose and subsequently changed it. I used it for nearly two hours after the change but towards the end, the machine stopped going forward in forward. It would still push backward IN FORWARD!!! So fluid levels looked a bit low, I have topped them off. I have run the machine for a few hours, no go. Lifted the wheels off the ground and run for 20 minutes, no change. Any ideas? Can air have caused this and how do I remedy? If not, what's next? The hi pressure forward tubing inside the trans? Any help is appreciated...