I’ve had The Dohenny Discovery for about 4 years. Lately it is not cleaning the pool. The impeller is clear, the filter basket is empty. Initially I thought it wasnt able to pick up debris and another user here suggested that the drain flap might have been warped. That appeared to be true, so I replaced it and have a nice seal now. The robot is now picking up debris , but it seems to really just go back and forth, over the same areas repeatedly, ignoring 90% of the pool (the truly dirty parts!). I don’t understand, the unit stays on for the whole 2 hour cycle, seems to be capable of getting around the pool, brushes the tiles and has bubbles coming out of the top of the unit. Any ideas on what’s going on with it? Trying to determine if it’s at the end of the road or worth repairing.