So, we have lamps and switches working.
Found an unattached wire in one of the switch columns, that got them all working. Couple of the rollover switches needed a little adjustment, now working fine.
Lamps - found 3 next to each other where I'd soldered the wires to the wrong end of the diode. Fixed that and that stopped the "double blink" issue. Found 3 lamps that weren't working didn't have a bulb in (Doh). Found 2 others where a wire had come adrift. So they're all working fine now.
Ran through a coil/flasher test and they all seem good, the autolaunch is even kicking on the "unused" driver which is good too.
GI wouldn't switch off in test, found that I had a connector trapped underneath the driver board, so freed that up and connected it, all good.
On the subject of GI, can someone tell me why I forgot to install the pop bumper lamp socket? I've got back ache from leaning in at some stupid angle trying to fish those through and get them soldered up. Done now though.
Something I'm going to need to work on is making some changes to pinmame to drive those RGB lamps via the Arduino. The Arduino code I already wrote should do the job just fine, I just need to persuade pinmame to talk to it and drive the lamps white when needed. But that's software, for later.
Now I'm going to start fitting the rest of the playfield back on.... getting close !!!!