My friend had a Marshall Valvestate head and it used to make a rumbling noise. He found out that a large percentage of them had a manufacturing problem. I'm pretty sure it was made in the mid nineties. Now, a coworker of mine wants to buy her kid a Valvestate 100 combo amp. I don't know how old the amp is.

Are any of you guys aware of problems with these Marshall Valvestate amps?