Hello ! I'm having issues with my Polaris 360. I'm a pretty "new" pool owner (2 years) and never had any issues before  - so I'm still learning ! I have an inground pool (plaster), DE filter that runs 12h/day

Here's my issue: my old back up valve wasn't working anymore, so I ordered a replacement. I replace both the case and the mechanism. New valve worked great for a few days, then started to get stuck in reverse mode. I took everything apart, it looked fine (and clean since it was new !). I contacted the reseller, and got a replacement mechanism. New one arrives, same problem : after a few cycles, it get stuck in reverse. I noticed a lot of water coming out of the pressure relief valve (from the quick disconnect). So I changed the pressure relief valve. Polaris and back up valve were working fine for a few days. Yesterday same thing happened again, but this time I had a hole in the hose. I fixed the hose (remove the broken part, it just shorten the whole hose from 5 or 6 inches), but it didn't solve my issue. 

I checked the RPM, it's 30 (I had to remove the back up valve to do so) - so this looks ok.

I'm at loss with what else to check/replace - can anyone help me troubleshoot it ?