Polaris 165 randomizer ball goes to one outlet and stays there,causing the cleaner not to change directions and stay in basically one area. I have sanded the piston and randomizer bar with 600 grit sand paper,gently pushed up the gaskets. The randomizer bar is moving back and forth but when in it's most out position the ball is not releasing from the tube it has blocked and floating in the chamber until the bar directs it to the other side or the same side again. All 4 exhaust tubes are clear,no obstructions what so ever. I did notice that the black tube the piston rides in was smooth until approx. 1/4 inch from the open end. I had to use just a little more "pull" to get the piston out. Could the piston not be fully returning and causing the randomizer bar to not reduce pressure enough for the ball to float free?? Just a guess on my part. I'm "stumped" on this one!! Any suggestions on what to try next??