My feeling is one of the trough switches needs re-adjustment as it is preventing the ball from moving over it. Next time it happens, open the door and look at the positioning of the ball. The switch assembly is easily removed from underneath if needed. I think removing the apron and simulating the fault will prove the issue. From memory, the apron is difficult to remove due to the positioning of the right hand bowl ramp.

Yeah , I already took the apron off last week to clean under it and had to remove the bowl , which is easy enough.

Will let you know the outcome, may well be a switch adjustment .. will see soon