Update -- took it to the pool store, they looked inside and everything was ok. Did find a little piece broken off the housing, so we replaced housing and it's better -- at least it's not falling over on its side -- but it's still going in circles. Hose is floating, not sinking, and all floats appear equally spaced. When we pull hose partly out of water (including backup valve), it does go straight. We had already replaced backup valve a few weeks ago, so that shouldn't be it (plus backup valve wouldn't affect straightness, would it?). Net is empty and brand new. Any ideas?!?!