[Station X]

A circuit diagram does not show actual routings or commoning points. Think of it as being like a London Underground map rather than an OS map.

R18, C27, V4 SG, R12, R9, R7, L1 and R1 should all be connected together, but not necessarily in that order.

It might be easiest just to do a continuity test between all those points or, with the set turned on, check for HT on all those points.