The booster pump starts out strong and the Polaris works fine, but after a couple of minutes, the sound of the pump changes (due to water no longer passing thru the pump, I assume), the outflow hose gets soft (no water passing) and the Polaris basically dies (usually in the deep end, not sure if that is significant). I have hooked up a couple of different crawlers and the same thing happens, so it's not a Polaris malfunction. This just started happening and is a change, it used to work just fine. I don't see any obvious leaks at the booster pump. Any suggestions? Thx.