Activate the Slide. IF the HWH pumps comes ON, it is HWH Hydraulic.
IF it creeps IN, then the extend/retract solenoids(2) are leaking internally. Under warranty HWH replaces BOTH. If out of warranty you replace the Extend solenoid if it slowly retracts slightly when out. Before replacing, open BOTH solenoids manually and operate the pump for 10 to 15 seconds and then close the valves. That removes any possible trash in the needle seat of the solenoids. Then observe for a few days. If it still creeps, I would replace BOTH. Doug