Hello. This is my first actual post since my introduction post. Thanks for a great, and educational forum. I found you guys doing research for ....this I purchased a late 80's JCM 25/50 head (Black Jubilee). Well, I had some trouble with it right away. First time I plugged in it sounded pretty damn good (Marshall tube amp... Duh). Straight in, no pedals. About 2 minutes in, it began to cut out. It acted like a bad cable, or corroded input. It fizzled in and out. Tried a new cable, speaker cable, and different cabinet. I unplugged it, and checked for loose tubes, bad connections, and all the stuff a novice amp guy can check. So much for a good deal. I delivered it to the smartest amp guy I knew. He went all through it. 137.00, and a month or so later, I picked it up. I played through it a few times with no problems. I used it for about an hour on night, then... Boom! Same symptoms. I parked it. Eventually I took it back to him. He said he had to play it for a day or two before it acted up for him. Long story short... It's working so great all of my Fenders are getting dusty and jealous. I could tell you what we found, but I thought some of the gurus might want to guess..