In the back box, behind the translite. Page 1-60 in the manual.
As other pointed out, check the high power interlock switch on the left side of the coin door opening. Two fat white switches there, top one is high power interlock. With the coin door open you can pull the knob out to check. If things work then, make sure the flap on the coin door that closes it is bent over enough to close it good. You can check that switch too and see if the wire connectors are on tight.
I've attached a picture ( from a WOZ, wire colors might be different ) to give you an idea.
If you leave the key in the lock, pull it out slightly so the lock doesn't turn. If door is loose, bend the cam on the lock a little to tighten the door.
LTG : )
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