Hi Angie,
I’ve just tried this and it’s very simple in theory.
It probably depends on your model specifics but this is what I did...
Turn the mains power off first.
Remove the main top cover, mine had three bolts on the back, at the top, clearly holding the top on. Slide the cover back and lift up.
Look behind where the dial is, mine had the back of the circuit board, where you could see red clips holding it on.
I pushed each of the four clips, and the board popped off.
With it off, it drops down slightly and you can lift it up, turn it over, there you will see the copper contacts.
Wipe off, use IPA if you have it, as it’s non-conductive of electricity, or just a soft dry cloth, don’t use water or a cleaning agent.
Mine had a film of slime on it, which may have been protective grease, who knows.
If you now look on the back of the dial (still attached to the machine), it has 3 or 4 copper ‘fingers’ that would make contact with the circuit board when it’s attached.
Wipe these too, be careful not to bend them.
Clip the board back on, making sure it’s the right way up, and put the top cover back on.
Then turn it on to make sure it all still works as expected.
Hope that helps.