We recently had a problem with one of our HWH jacks – it intermittently wouldn't retract by itself. A call to HWH connected me to some very good technical advisors. They helped me to understand what my problem was and got the part shipped to me based on the diagnostics that I did myself. Fortunately, I am a professional auto technician!
You should have a model number and serial number on your main pump motor and manifold unit if it's similar to the one that I have. Our system uses only one pump and motor to operate the jacks and the slide rooms. Our system also has model numbers and serial numbers on each individual jack. (Unfortunately, the operator's manual just has generic info on possible systems available for our coach.) These numbers will definitely help when you call HWH. They may be receptive to speaking directly to your technician and possibly ship the parts to him.
You may already have this, but their website is www.hwhcorp.com
and their phone is (800) 321-3494, 8am-5pm Central Time (M-F).
Good luck. I hope this is helpful.