This subject has probably been posted a lot. Have a five year old Pool Vac Ultra. Been satisfied with it. Every so often have to replace parts, but that's okay.
Here is the problem: The unit will get stuck on a step in the shallow end. The inlet on the bottom of the unit essentially gets stuck right against the top of the step and does not come off unless I pull it off myself.
The shoes are not worn (I looked at the indicator). The pressure is not too high. The flaps are intact. I changed the gearbox last season. The pods move properly. The rear flap adjuster is in "position I".