There are a few Jinma dealers that read here regularly that can answer the rebuild parts kit price question.
As for manuals, there are really none out there that are going to walk you thru the process step by step. Johns jinma website is a wonderfull resource for the Jinma 200 series tractor, and someone may have posted a step by step repair of the lift box there.
johnstractor
I can go over the basics here:
1. Remove the links between upper and lower lift arms, and the lower lift arms.
2. Drain hydraulic fluid out of lift box. The drain plug is located at the lower left corner of the rear plate on the lift box where the toplink attaches to the tractor. It looks just like a bolt, but it is not evenly spaced like the actual plate mounting bolts are. I find this is easier with the tractor raised at the front(driven up on maintenance ramps?). A funnel and a hose into a larger container is also helpfull as it is difficult to hold a container up under the drain hole.
3. Remove the bolts around the toplink attach plate and the plate itself.
4. With the plate removed, the upper lift arms will be able to be rotated up, and I believe this will allow the internal 3PH lever to rotate out of the way of the piston.
5. Remove the piston out thru the back and replace the seals on the piston.
6. Apply hydraulic oil to the seals for lube and reverse the disassembly process...
Good luck
