Quoted from beadwindow:To start a game I have to manually activate the Start relay which stops the score motor
I'll start with this observation. The Start relay is an interlock relay with two coils, a Latch coil and a Trip coil. Based on the schematic and what you've described it sounds like the Start Trip relay is firing just fine to get the score reels to reset and such, and that it's the Start Latch relay that's not firing at the end of the reset sequence. If that's the case have a look at the switches that control the Start Latch relay coil:
MiniZag Start relay (resized).jpg
If you're not sure which is the Score Motor 7B switch, have a look here: https://pinside.com/pinball/forum/topic/sky-kings-power-free-play-and-top-hole-issue#post-4457680
/Mark