I have a Polaris 280 - have had it for ten years, with very few issues. Lately it has begun "running over it's hose" causing the back flow valve to loop underneath, and then it just sits there.... I replaced the back flow vale and it is only mildly better (the BF valve no longer drags the bottom of the pool, but the Polaris still ultimately runs over the hose....). I have replaced all of the swivels, just in case. In doing so, I noticed the hose is not floating along the top of the pool. It comes off the relief vale, makes a deep "U" downward, comes up to the top of the pool to then bend down to the Polaris, with the BF valve bending at about a 90 degree angle above the Polaris...
Other than replace the BF Valve and swivels, I have not done anything to the Polaris or hose. It just started doing this about a month ago. (In South GA, still in the 80's).
All floats, etc are in place as they have always been.