I have a 1952 ZAU that I have added hydraulics too with salvage yard parts. The pump and lines are in great shape and work as they should, however, the hydraulics won't even try to hold a load. I tried to pick up my 12' crusher and it picked it up fine but as soon as you kick the lever back it falls to the ground. All of the books I have for the lift just tell me to replace anything that looks bad, but I don't have any idea what everything is supposed to look like in the first place. Can you rebuild the valve in the reservoir? Are there some internal o-rings I missed the first time I had it apart?