I have an intermittent mega bass switch. When I switch it to norm, it will crackle and and the mid will turn on, although it is switched to norm. I have taken the DD9 case off and it seems to be some kind of opitcal switch rather than a mechanical one. As I use this daily I have to out tape over the mega bass switch to stop it crackling and the mid kicking in.

Is this a faulty switch or could it be repaired with contact cleaner?

My DD9 also has a crackly volume pot. Again is this possible to do at home or is is it another repair job for the pros.

Thanks

Yesterday I put a very very small amount of contact spray into all my DD9 switches and volume pot. Also the Mega switch.... Does wonders as usual  Its a 2 min. job... 

Thanks for the advice Michiel, contact cleaner solved all the problems. I now have a perfectly working DD9. Thanks again.