Help! Amph goin' south...

[Katastrophe]

...and I don't mean to Mexico for the winter. I was getting ready to do my weekly guitar lesson (I give lessons to my stepdaughter's stepbrother, and in exchange my wife's ex pays for my stepdaughter's martial arts classes), and I set up my amph for some screamin' solos. The volume started going up, then almost silent on me. What's happening here? Is my amph crapping out on me? I hope not...

Help, brother fretters!

[oldguy]

What kind of amp is it? Is there any kind of power supply prob.?:confused:

[Spudman]

Is it a tube amph? That would be your weakest link. I'd check those first.

[Katastrophe]

Sorry I didn't say in the first post... It's a Crate 120 watt solid state amph. No tubes, unfortunately.

[Spudman]

Have you tried Guitar>cord>amph? That eliminates other variables.
Otherwise it sounds like a speaker jack problem or else it's just ready for the glue factory.