How 850 Ashtrays Work
The design is such that the spool sits in a couple of grooves in the back of the ashtray sub-carriage (see Figure A). The copper coil must reach over the top of the mobile sub-carriage to a silver peg that will be lodged in the hole adjacent the light window of the housing (see Figure B). The spool moves with the sub-carriage as it opens and closes, while the peg stays affixed the to the immobile housing.