The other day when i was mowing with my sentar and the drive belt went out. I knew what it was right away bc it had happen once before. So I opened the bypass valves and coasted it on the trailer. My mechanic fixed it right away and had no problem driving it back on the trailer. But as soon as i got back to the job I couldn't get it to back off the trailer. The left wheel operates perfectly but the right wheel has no power, (basically just enough to spin the tire when you have the back wheels jacked up off the ground) I checked the reservoir right away and noticed it was low. After filling it to the proper level I bled the lines as instructed in the owners manual but it did not seem to help at all. Is there any other way to bleed the system? Also, there are no visible leaks on any of the lines. And strangely after the mower sits for an hour or so it drives and works fine for about 30 seconds and then the right wheel loses power.