"Auto skipping. Example, from one effect to another".
Is it always so, or only sometimes?
What type of effect? Is it happen at the all Type of parameter? It can be observed from the changes sound is heard.
Yes
"it just need cleaning", but, which parts are cleaned,and how he did? Is it potentiometer?
And if he simply cleaned by spraying contact cleaner, this is not effective at all, because it does not touch at all the inside of the pot.
Potentiometer need to be replaced, but if it is difficult to find, open the back lid of potensio. Fix the inside (you have to understand the potentiometer structure inside).
ME70 pots are look like this :