John Deere 5210 lift problem. I have a JD 5210 model since 2000. The lifting arms are lifted very easily and slowly. I changed the filter and fluid and cleaned the suction filter. When I start the engine without additional equipment, the levers rise quickly, but I can stop them with my hand. If additional equipment is hooked, then the levers are raised very slowly. What could be the problem? What else can you check?
My first suggestion is to purchase a technical manual. There are a number of tests to help you identify the problem.
After that, such problems began, How did everything work before? Do you have a bootloader, how does it work? Probably a pump problem.
Turn the pressure relief valve about 10 times to release the air. Is there air in this case? When opening the safety valve, negative pressure can build up. To regulate the pump, you need a pressure gauge, flow meter, and flow control valve.
Perhaps there is a hole somewhere in the highway.