Not sure I've heard of this fault happening to anyone else's MXR M108 and I gave it a google search with no help. After that, my next course of action is to ask the people of GG&A.

Anyway, the problem at hand is a near constant crackling noise. It sounds exactly like the noise you get from a faulty/dirty jack cable or socket when you twist the jack around. That crackly dirty sound. Only, the problem here is that nothing is moving and none of the cables I've tried were dirty. It's not a case of either the input or output moving, and when I do move them it doesn't increase the amount of noise that comes through.

The "moving dirty jack cable" sound is completely random and has made it pretty much unusable on the clean channel of my amp. I opened it up to look for any obvious spots of dirt but didn't notice anything. This is probably due to my unfamiliarity with the jack sockets used in this pedal. It's the same sort you find in the back of a guitar speaker cabinet, rather than the smaller version that you find in Boss pedals and most guitars. I'd know where to check for dirt on these.

I don't know what to do, or what contact cleaner to use if that's the fix. The warranty's expired so no use going down that road. Give me suggestions guys!

"Air created the greenness. And once you've got something, that leads to otherness." - Karl Pilkington.
sounds like a circuit problem to me vs a battery, cable, jack, ps

i'd get it to someone who can trace that out for you and resolder/replace the faulty part - assuming that is what is wrong.

if you are not sure how to go about the next steps maybe post in the Only Pedal Board thread which is currently on page 1 here.