The other day, I got a call from our ace mixing guy. He was in our music studio, about to mix a short, live broadcast on a Mackie Onyx 32.4. He was panicked because the left main buss was dead. With the resources on hand, and because I was 40 miles away, there wasn't much we could do other than a mono mix down further up the chain. It was less than perfect but it got the job done.
A few days later, I went to work on the problem. My first thought was an unhappy one of major surgery on the console, then I had a hunch as to what the cause was. Sure enough, the insert jack contacts for that buss had gotten flaky from a little oxidation on the contacts. I gave the jack a good washing with Caig DeoxIT D5, followed by plenty of exercise by plugging and unplugging a connector into it, then a spritz of G5 Gold to keep the oxidation from returning. Now it is good as new. Not a moment too soon as Chick Corea, Jack DeJohnette and Stanley Clarke are visiting for a performance on Friday.
I also found that one of the input channels was suffering the same fate, so I went through all of the inserts. This is a common problem for any analog console with inserts. I've had the same thing happen on Soundcrafts and others, not just Mackies. I'd be willing to bet perfectly good consoles have been retired just for dirty inserts. Those two Caig products should be in every audio person's tool box.