[mole42uk]

There's more. The record function does put a signal on the tape, but only if it's heavily over-driven and the output is distinctly iffy. I've abandoned work with the erase head for now, I scrubbed a tape with a permanent magnet so at least there's no previous content, just hash.

I've checked both the input channels with a suitable signal, the VU meters indicate correctly, there's a believable signal at the collector of the output transistor of the record PCB, but the only signal that gets as far as the record heads is the oscillator. I swapped the two record amplifier boards and the fault remains, I checked both channels using the same settings and the results are similar.

There's obviously a common problem somewhere I haven't yet established - the record relay clicks in and out as expected, the contacts look clean. I can't see anywhere on the circuit that might give me an aha! moment.....