Gottlieb usually used two power switch mounting plates per game. Note that the center portion of the plate has been stamped to have a slightly recessed circular area. What GTB would do is to orient the top plate so that the bulging-out side of the recess faced the switch. The nut to hold switch shaft to the plate was then installed to attach the switch to the top plate.

Next, the bottom plate would be oriented so that the bulging-out side of the recess faced away from the switch. The bottom plate rested against the top plate, and the recessed portion of the two plates created a space for the switch mounting nut, while also covering the nut so that it could not be unscrewed from outside the cabinet. This double-plate assembly was then screwed to the inside of the cabinet on the wooden switch block to mount the entire switch assembly to the cabinet bottom.

In short, you may have an "extra" switch mounting plate (the bottom plate) on your NOW game that you can borrow to use on your Astro. If you do this, of course, neither game will have protection against someone unscrewing the switch mounting nut from the outside of the game. Unless you plan on putting these machines on location, hopefully that isn't something you need to be too concerned about.

- TimMe

This is great advice, I just want to mention that GTB schematics are not available for free download online. The current copyright owner is still licensing these schematics, so the good news is that you can (and should) purchase copies from The Pinball Resource if you don't already have them.

- TimMe

Nope. Don't use this switch. The power switch for Astro is on the primary side of the transformer, running at 120 VAC. EM pingame transformers of this vintage typically pull between 1 and 2 amps at 120 VAC when the machine is idle, and probably 3 amps + under heavy load (during game reset, for example).

You can always get a rough idea of what a circuit like this will need to handle by looking at the primary fuse rating. The GTB games of this era were typically fused at 5 amps, so you can expect that the primary side of the transformer will (at most) pull about 66% of the fuse rating (in this case 3.3 amps) under normal usage.

If it were me, I would want to put in a power switch rated at 120 VAC @ 10 amp or 15 amp. The extra margin of current capability is insurance against having the switch fail prematurely under normal usage.

- TimMe