Thanks Lawrence - confirmation that I have R17 wired up properly i.e. physically connected between pins 8 & 7 of the EABC80 valve holder.
The inner conductor of the co-axial from the volume control is connected to the tag strip below and between V4 and V5 in the third photo from Post#9 but the shield has become disconnected - where should that go physically?? Looking at the schematic I think that this should also be connected to pin 7 of V4?