My Quattro worked well for years in a large plaster pool. Now in my smaller Pebble pool it gets stuck at the wall in a 45 degree angle. I tore it down and replaced the wheel bearings, checked the gearbox, etc. Strange thing about the wheels/gears, one side is definitely the power side with a metal drive gear, and the other has a plastic gear and much less power - also that side is much easier to stop rotation with my hand and slips. It would appear the gearbox is set up for occasional slippage so the unit rotates for a period of time and picks a new direction, but even with that the 45-degree gears don’t always seem to fully mesh and I can’t tell if that’s intentional. Anyway - the tires appear ok, almost sticky and coupled with the rough pebble pool finish one would think grip isn’t a problem but alas this thing is constantly stuck at the wall in a helpless position. I’ve got the main pump at 3450rpm and a PB4-60 booster. I’ve tried adjusting the rear jet up/down/sideways with no effect. Any ideas?