More circuit help required please

Evening all, I wish I had the ability to take a board layout and turn it into a logically laid out schematic but as yet I don't. Video sync on my Executel 3910 is still running me round in circles so could one of you fine folk take a look at this board layout drawn as best I can: http://www.binarydinosaurs.co.uk/STCExecutelSyncCircuit.jpg ...and let me know what it does please? The chip on the left is a Plessey MR9735 teletext video driver wired to run permanently in 'off hours' mode - you can see 'Sync In' is just pulled high so the chip doesn't detect any incoming sync and is supposed to generate its own, which it doesn't even though all external clocks are present. Resistor values are correct as far as measuring them with a DMM goes, the diodes aren't actually 1N4001s but I can't read the printing on them. Both transistors are BC548 NPN. The area labelled 'MON' is a 14-way ribbon cable that goes off to the TV driver board. I'm feeling pretty dumb at this point. Logic and truth tables are more my thing, current flow is something I'm learning slowly. Cheers! -- Adrian/Witchy Binary Dinosaurs creator/curator Www.binarydinosaurs.co.uk - the UK's biggest private home computer collection?