have john deere 5320 with front end loader. I just picked up a rear hydraulic ditch bank mower. I hooked the wet lines up to test the cylinders on the mower, when I did , I got them backwards. So I disconnected the lines, and was going to take the tractor to the shop. But, now my rear lift arms will not lift. The rear lift arms were working before I hooked to the mower. My front end loader operates like it should. I checked the hydraulic fluid and it checks fine. One thing I noticed when I checked the the hydraulic fluid is that if the tractor is running there is a hissing noise coming from inside the tube were I check the hydraulic fluid. I don't know if that is normal.