I haven't had to work on those for years, so I don't remember the ins-and-outs of adjusting them. However, when I did work on them, the trouble-shooting and adjusting process found in the manual always solved the problems I encountered. You'll need to verify your model, though, and make sure you're working from the correct manual.

Keep in mind that, at least on the units I've serviced, the Polaris unit itself ONLY moves forward. The back-up valve worked by cutting flow to the head (wheels) and using that flow to create a reversing jet. If your backup valve is stuck in the the reverse cycle, then your unit would back up as you say.

It's much easier to tell what's going on if you examine the unit -- while in operation -- on the pool deck. Obviously, this works best if you are in a swim suit while doing so.

http://www.polarispool.com/~/media/Z...0.ashx?force=1 (manual)

http://www.polarispool.com/Pressure/...280.aspx#pFAQs (FAQs)