I think my wife is cheating on me. I am working on different plants and, as you would expect, travel a lot. I have been noticing strange things happening when I get home. Her cell phone rings and she steps outside to answer it or she says, "I'll call you back later". When I ask her who called she gets evasive.

Sometimes she goes out with friends but comes home late, getting dropped off around the corner and walking the rest of the way. I once picked up the extension while she was on the phone and she got very angry.

A buddy of mine plays guitar in a band and he wanted to borrow my guitar amp. When he came over to get it he told me that my wife and some guy have been to his gigs.

That's when I got the idea to find out for myself what was really happening. I said, "You can use my amp but I want to hide behind it at the gig and see if she comes into the club and who she comes in with". He agreed.

Saturday night came and I slipped behind my Marshall JTM45 half stack to get a good view. I could feel the heat coming off the back of the amp. It was at that moment, crouching down behind the amp, that I noticed that one of the preamp tubes was not glowing as brightly as the other three.

Is this something I can fix myself or do I need to take it to a technician?

Thanks