Showed up set to bridge mode, had to open it and find the switch. Turns out not on the side with the diagram. Do spot a toasty looking resistor bottom left though. Still tested right, luckily as it was missing a stripe.
Right side this time, showing the classic K135 and J50 mosfets. Hand marked bridge/stereo switch on the pcb to the left.
Laney VH100R, made a bunch of noises and blew a fuse.
A shorted power valve, a miles out of spec (like, measured a couple of meg rather than open) grid resistor. Suspect someone tried a ‘fix’ by swapping positions before selling this as ‘working’. Couple of dud pres too.