Machine should be reasonably level in its position. Check that the tub bias spring is attached. Switch itself and it’s wiring are prone to corrosion problems. Wiring can also work loose due to vibration. Fault can be generated by control board, but this is unusual.
Many thanks for the prompt reply Penguin45,
Yes as you suggested the out of balance switch was corroded. It’s Sunday night here and I cleaned it up and it I’ve just finished the wash. Machine is working a treat and the wife is very happy!