Fault U13 keeps appearing on our Panasonic NA - 148VG4 washing machine. Adjusting the load as advised in the Operating Instructions booklet doesn't solve the problem. The drum appears to move in and out as it ramps up speed and then stops, presumably because the movement of the drum is beyond limits (as detected by sensors). Could this be an issue with the main drum bearing (the machine is 8-9 years old)?