[McMurdo]

stick a new GZ34 in,you'll be ok I'm sure. if there's any doubt, Marshall will happily talk to you about the amp, they're that sort of company.

Guitar players a re a funny bunch, so replace the valve rectifier with diodes at your peril! Apparently, a sagging rectifier adds some sort of creamy distortion or other rubbish.

Wonder if you could fit a surgegard in the ht line to prevent rectifier stress. Even a good one will flash if you operate the standby switch. Silly circuit.