Electrolux ESL 6114 cycle never ends

Hiya all ,
First time poster so hiya in advance. I have an electrolux esl 6114 dishwasher that for some reason last night tripped my rcd. After resetting in the middle of the night i went back to bed but woke 2 hrs later and i could hear the dishwasher still running. I went to investigate and found the program select wheel seemed to be stuck holding the wash cycle in place , i moved the wheel and the cycle continued. Tried a rinse only cycle and that completed fine next day. Did another load and same thing the wheel sticks mid cycle although the wash does seem to have completed and dishes where clean
1 thing of note. I have no idea how old it is as it was inbuilt when we got the house 2 yrs ago

Any help would be muchley appreciated