I have a KRK Rokit 6 with a tweeter that I'm hoping someone can tell me how to fix. I've heard the same sound from a speaker that had squirrels get into it. If that were the case here it'd more likely be mice. Basically a crackling whenever the speaker is switched on. I tried swapping the actual tweeter with my other speaker. The one that wasn't having issues still isn't, the one that was having issues still is. So then I opened up the back and tried to see anything wrong. No droppings or anything else found. While I was in there I also sprayed compressed air and DeOxit on basically everything and let it dry. No change.
Any other ideas before I replace the whole thing?