I have an older Gravely ZT 2348 XL zero turn and only the right side wheel will go. I had released the hydros to push the machine and afterwards closed the release bolts down, backed them off a quarter turn. Start her up, and at first I could go forward but then the left handle got really stiff and stopped any movement. If I pull hard on the left side the handle can move a limited amount. I checked my reservoir and it is WAY above the dipstick mark. I have no idea how that happened. Could that be the culprit?