I've got a Boss NS-2 that I've used for ~6 years without issue. I recently took my board apart to redo all the effects and noticed that the output of the board was inconsistently dropping and returning and there was an occasional crackle when cables were strained. I took everything to pieces and isolated every pedal and found it to be the Boss NS-2. There's no power issues (in terms of it not getting enough power or it trying to power other pedals). In complete isolation the sound issues happen the same as if it was in my board - so it's not the other pedals that's interfering with it here. It's powered by a 9V adapter (of which I've tried several of different brands), not battery powered.
It's out of warranty and Boss/Roland never got back to me with engineers in my local area (one tech support guy from Roland recommended I just replace the thing as it'd be less hassle but I'm loathed to do so as it was £75+ postage and I've had pedals last WAY longer with more abuse). I have tried stripping it down and attacking it with contact cleaner as one of the jack inputs definitely crackles but not the pots (they're as clean as a whistle).
With that in mind, what other steps or tricks can I try to salvage my beloved NS-2 (or any pedal for that matter)?
Update 20th Dec
I've taken it to bits and I figured I'd probably replace it anyway as the repair cost is almost the same as a replacement. In doing so I think I may have stumbled across the issue - a bad earth. Temporarily I've connected a "manual" ground from the input to the output jack (not the FX send/receive loop) which seemed to cure it before I put it back in the housing. I've re-bathed the board in contact cleaner to ensure all contacts are squeaky clean, all jack inputs & outputs are sprung properly, all solder joints have been redone just to be sure so it seems like there's a problem with the board itself - specifically with the grounding however the metallic/digital hiss & dips in sound still exist - albeit a slight bit less than before.