Hi @beadwindow, my AAB journey started as I thought the Credit Lamp in the apron was not working and ended in my wiring a DIY "Added Ball Kit". My Rocket III is now switchable between Replay and "Shoot Again" (- which is what it says on the backglass). Yours will be very similar but I don't see a a lamp in the apron.
I have since found information in the 1969 Parts catalog that this conversion kit approach started with Rocket III
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The chronological games list then highlights clearly those earlier than Rocket III had an AAB model * and later that were convertible using AAB Kit **. (All machines until Cosmos apart from The Wiggler for some reason)
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I worked out the wiring for the Relay from the Schematic, I'm happy to help with this if needed.