Thanks Ken.
Made some progress (it helps if you put the correct BC547/557s in the right places - not sure how I missed that one!)
Still not right though and I've redone the GHJ and C + wiring (I had to remove it to replace the few erroneous transistors) so there's definitely nothing amiss there.
Now I have these problems:
- still doesn't advance the sequencer step sending a gate/pulse to the UP input on the common board
- seems to advance backwards if a pulse is sent to DOWN with the caveat that when it gets to step 1 it doesn't loop back to 4
- you can select stages 1, 2 and 3 with the push buttons OK but when you select stage 4, on letting go of the push button, stage 2 is immediately selected
I'll keep plugging away but if any of that rings a bell, a pointer or two would be the saviour of my sanity right now! :)
Cheers,
Neil