Heated yo the broken screw in the neck with the soldering iron until there was a hot wood smell, let it cool and got it out with some pliers. New ones in with some vaseline on and all good.
Quick job today, bit of solid state amp work which isn’t my usual thing, but it was an Ashdown belonging to guitarist in a mate’s band, and in my experience Ashdown amps have been easy to work on and Ashdown have always been very helpful when it came to parts and pointers when I’ve been in touch with them.
Screws not in as I took this after sorting the issues, but nice open layout, preamp and power sections well spaced so no interference or hot things cooking anything else, everything nice and accessible. Mesa and Ampeg could learn from this. Board mount everything though as is a cheap amp.
Bunches of dry/cracked joints here was the problem, resulting in a lack of apparent power and cutting out. Suspicion its the extra vibration as well as power demand that triggers it when being loud. Resoldered them all, screwed it back in, cleaned off the thermal paste that I managed to cover myself in, good to go.