Lost power. Hello, I have this normally great sounding Deluxe Reverb (1966-ish). It was working

Question

Hello, I have this normally great sounding Deluxe Reverb (1966-ish). It was working perfectly when I last turned it off. I wnt to use it again recently and it has no power. When I turn up the volume it has kind of a compressed sound and no balls. No smoke or symptoms that would indicate a major failure. Could a tube have gone bad? Any thoughts would be helpful.

Thanks,
Jack
RI, USA