If you are getting water through the cleaner, a few reasons why a 380 would not move:
1) bad bearings inside the motor assembly
2) broken/snapped drive belts for the wheels
3) cracked supply hose and feed pipe(inside the cleaner)
4) see my last paragraph. Water pressure is causing the motor assembly to bind up, locking the gears to a complete stop. Old age of sweep.
tbenton wrote: Wheels turn fine manually
Do they spin when the pump is on? Or just stay idle?
tbenton wrote: The only thing he found was one broken zip tie on an internal hose we were sure that was the problem
That's the manifold supply hose. That feeds the motor wheel which makes the wheels turn. That would cause a Polaris to park at the bottom of a pool. The best way to repair those when they slip off, is to either replace them or heat them up in warm water, quickly slide them back on and zip tie them so they lock.
tbenton wrote: The little 'O' ring was a bit loose but it was in good condition but he wanted to change it and see if that could be it. Well of course he had just used the last one to fix another 380 so he ordered me one. Is it possible that it being loose could possible cause the cleaner not to move at all?
The supply pipe O-ring wouldn't stop the sweep, just leak water where it shouldn't and make it operate sluggishly.
tbenton wrote: In 27 yrs and only on our second Polaris we have never had the vacuum out of the box and I don't want to have to resort to that.
13 and half years of replacement sweeps is not un-realistic. They don't last forever. At some point, the entire Polaris frame and body fail completely and just cannot be rebuilt anymore. When I say fail completely, I am addressing the fact that the plastic frame, due to age, is out of specification to hold all the little parts together and in sync as they did when it was brand new. When that happens, new parts do not work right, press against other parts and freeze up gears. Or do not align correctly when the water pressure flows through the sweep internal mechanisms. I realize they are expensive at over 400 dollars(US) a pop, but if this sweep is making your pool beautiful and enjoyable, that is definitely paying for itself many times over within 13 years.