HWH Hydraulic system problem - recommendations

On the end of the electric pump motor is a metal keyway. THAT can fall out and if NOT installed the motor does NOT engage the pump assbly. The motor will do as you state---spins fast because there is no torque on the motor. Remove the electric motor and you will see how this keyway engages. You will also see if it is GONE. Doug

The older Parker pump motors had this keyway. Since you have a 1997, the odds are you have this keyway. Newer HWH pump motors do not have this keyway