I am having the same problem with a H20T, tilt, sideshift and steering all appear to be working, but lift is weak.
Empty forks move as if all were well, but with a load on lift is slow if at all.
I checked the pressure at port marked MP on the control valve, and get a reading of 1500PSI. The internet shows this pump as being able to produce 320bar. (4500PSI)
Is there anyone who has a breakdown of the valve and where the relief valves and test ports are located for lift and other functions?
Any other suggestions and comments welcome.