And today i tackled the intermittent non scoring 4 bank drop target problem. I'd already cleaned/adjusted the switch PCBs and contacts, to no avail, so after having a read thru Clays Williams sys3 - 7 repair guides, he suggests replacing R204 - R211 in the switch matrix section to zero ohm jumpers to make switch triggering more reliable i decided it was worth trying, since the targets woud work for a while and the stop... waste of time as it turned out because it worked no better once i was done    

back to the drawing board... i lifted the playfield to study the switches again, armed with the circuit diagram and the maunal opened up to the switch matrix page.
notice in the first pic, the black wire that loops across to the other switch boards.. these should connect to the switch matrix "column" wire which is the green-violet wire 2nd from the left at the top. i eventually worked out that the wiring was wrong here.. there is no connection to the black wires, and hence no column wire connection to each switch. so the answer was to switch the green/violet wires with the black wire on the middle two solder pads (2nd pic). after doing this the targets now score how it was wired before it would still reset but not score, as the middle two contacts are for the reset (i assume) and the outer two are for the scoring action. how the targets would score at all the way they were wired is beyond me!!

after working this out, it dawned on me, that playing this game years ago that these targets never worked properly then! this was wired wrong from the factory!!

Anyway after cleaning adjusting the other switches as needed, removing and cleaning the seized kickout hole mech, and replacing a few dead globes and rubbers she is fully working now It DOES still have a an issue with the driver board interconnector, (new ones have been ordered) but for now i'll set it up in the lineup and play it for a while til i get around to the restore.