The other day my Crate V18 wouldn't make any noise even when I cranked the volume. I assumed it was the outlet and switched to another and it worked fine.

Then yesterday the amp was fine in standby but when switched on it would turn off and on every second. I could hear the speaker kicking in and out. So I turned it off again assumed it was a faulty power source. Today I came home and tried in in the outlet in my room, which is new, and had the same problem. Inspecting the tubes through the top grate I saw one of the power tubes glowing bright pinkish purple as the amp turned on and off. The tubes are less than a month old.

I have no idea whats wrong with it, could be the tubes but I doubt it and it could be something with the power chord or transformer but I don't know how to check. Any thoughts on whats wrong?
No, tubes won't usually make the amp cycle in and out like that. I'd check the fuse.
The fact that it's fine on standby makes me think that one of the filter caps is gone or that there's a bad solder joint somewhere in the power supply.
I'm assuming a bad solder in the power supply is bad but does it mean the amp is totally dead or is it fixable.