to Pickmaster - no no no - I NOT pointing in your direction at all !!! The mods you suggested is in the pre amp and this fault has to do with the power amp...no worries !!!
I had a tech look into it today - He measured things and wverything seemed to be fine - so we swapped the 6L6's to a new pair - and everything seems to work again ....... D***** I hate it when tubes crash...can be so expensive..
Anyway - I think i can solder on 2 new wires on the tranny, and then I need a new On/Off lamp (the housing has been melted as well) - and then it should be fine again. .... hopefully. :