many thanks , as always Martin.
I disconnected everything downstream from transformer I think ...
i.e 2 black wires disappear into voltage dial (rectifier?) and come out and feed into 1.6A fuses before entering(transformer?) via numerous waxed red & green cloth covered wires.
More wires come out from this transformer & supply tiny PCB.... I disconnected all items from this PCB thinking that is what you had suggested .. I hope I'm right.
Anyhow, , as soon as i hit P1 button the 1.6A fuse that feeds the green cloth covered wire going to transformer blew.
the other 1.6A fuse is OK