defourzE wrote:
Is it difficult to clean the pots ?
It's not that difficult, but a tin of contact cleaner is expensive for a once-off. It's also not guaranteed to help, but is worth a shot. You need to open up, and spray the contact cleaner in through the holes in the side of the pot (if there are any). If it still crackles, the pots need replacing.
EDITED TO ADD: Make sure to use the right stuff for cleaning, you want a potentiometer cleaner, not the greasy stuff