the wheel that controls the coffee grinding time of my coffee machine does not work

the wheel that controls the coffee grinding time of my coffee machine does not work and the maximum time is always activated regardless of how the control wheel is turned. they told me to change the card on which the wheel operates but despite having changed it I still haven't solved the problem. What element do you think acts to create this inconvenience? From the card starts a cable that fits onto another card (grinder connector) with a lot of components.... what should I look at to try to identify it; guilty element? Or is it better that I throw away the whole car as they told me in attendance... the fact is that it's a 400 euro car damn it