OK, sluggish hydro's are usually due to low high pressure settings. Very seldom have we been able to set up the pressure and fix the problem. If your hydro has a releif valve cartridge, sometimes the orings get hard and leak past the valve thus lowering pressure. Most of the time it is a combination of wear in the heads and the springs weakening thus 'floating' the motor head. The fix is precision milling the rotating groups and replacing or shimming the springs. On the dyna power we have 'fixed' a few by removing the input seal and using a D19 fire ring to shim the brearing thus the spring pressure. Best fix is to have a reputable rebuild with someone who can TEST the unit on a stand. cutting costs usually don't....