ok so my randall 150 valve dynamic head started to fade in and out and getting really gainy and i cant figure it out ive had a man who works with amps look at it and he cant find the problem. Any ideas on whats wrong??
So you are saying you've already had an amp tech look at it and they can't find the problem?

Get a new amp tech.

I don't know anything about that amp but since you say it is a valve amp my first guess is the valves are going bad. Probably power valves but could be preamp valves I suppose. How old is the amp?
Hey man thanks for the advice you were right it was the tube and now i got a new one and shes running like new