Marshall Valvestate 8080 no sound, no channel lights

[Hector]

First there was some volume fluctuation, then it cut out and the channel light went out at the same time. Is it the chip, or a discrete component related to it's operation? I would be grateful for any insights provided by the community. Anyone? G1?

[g1]

If a light went out, I'd look at the low voltage DC power supplies first. There should be +15V at ZD2 cathode and -15V at ZD1 anode.
schematics attached