Zinky Encore, volume fades, sound gritty

I bought a Zinky Encore 60watt Tube head, sounded great for friend that is an amp tech. He said he changed out all tubes, could not find problem, wiring is insulated with silicone
Sometimes when first plugged in the volume decreases a 1/4 and sound starts getting gritty. Has been non stop for a while.
I am an amateur when it comes to tech stuff.
Great amp and I have another Zinky Suppro head 60 watts, that is the same animal except has no effects loop. It is fine, more than fine,
Any reccomendations?
Thanks
Headshop

Bad power supply?

If it is a bad power supply, what all should I check to solve the problem?

Can't help you there, I was just guessing a suggestion. :rolleyes: I see you posted in the Guitar Tech's forum. Hopefully he'll have some insight. If he can't help, maybe try http://guitarnuts2.proboards.com/index.cgi?

Thanks I just became a member

Saw you are in Canada, watched the new Documentary on Rush, it was really good and went back to there childhoods and home movies.

That's on my list of things to watch. Also wanted to check out the Anvil 'documentary'. I wasn't a big fan, but it might be worth a watch.