[DMcMahon]

Thank you Mike for the very useful tip.

In fact long ago in my youth I used to do exactly that for awkward to reach valve pins and until now had completely forgotten about doing it !

By the time I had read your post I had already drilled out the rivets and shortly will unsolder the wires and will have a good proper inspection of the valve base (s) wiring and be able to measure all the voltages.

David