This machine is out in my shed, so while Kraig is away, i've had a look.
Coin door - there is only one switch - the other has had one blade snipped off and all the wires disconnected and taped up - dunno if this will affect anything?
If the remaining coin door switch is open - the machine will not turn on!!!!
If it is closed, the machine powers up and does what Kraig described (continual score motor turning and resetting the big bank of switches under the playfield) . Then if i open the switch, and as you said Strangeways, by tapping it, the score motor turns, the big bank of switches under the playfield resets once and then it seems ready to play....
Pressing the start button does nothing (credit wheel has plenty on it - and has been cleaned), whether there is a ball in the trough or not.
BUT, when the trough switch is closed, the score motor turns (but the bank of switches under the playfield do not try to reset), when the switch is opened, the score motor stops turning..hmmmmm.... no idea - but am enjoying the challenge of a whole new world of EM's!!