My st 3020 walkie intermittently shows a fault on the sem 0 led after the brake has been set then released, then when travel in either direction is selected, motor starts then contactor drops out, brake is applied and sem0 displays 5 flashes. If brake is activated again then released, the contactor recloses. If red belly switch is then used momentarily before selecting a travel direction then the travel selected operates as normal. It doesn't do the fault every time brake is selected but once the fault occurs it won't operate normally until the belly switch is activated and released. I have checked the diagnostic codes for 5 flashes but found nothing wrong. It operates normally 99% of the time. Any suggestions will be appreciated