Hey Pacman , Really sweet work man .
It looks like all the hard work is done . Nice job with the Cabinet and Paint .

I have a "Jet Rocket" here , with schematics .
I dont have the " Killer Shark" schems to work from .I think both games would be wired almost the same way.
So here goes ,
The "Safety Shock Relay" goes through the Coin Sw , Safety shock (Sw on its self) then to Game Relay.
" Safety Relay" Travels through Switches on itself ,replay relay, coin relay ,replay button and replay relay then to Game Relay.
But switches on all these relays are part of the chain .
Score reset coil . Replay Release Relay .Replay Meter, Play Meter and Hold relay.Coin Swt.

Double Check for Jammed coin, credit button even the Test switch.
Check resistance on all those small coils too ,And Meter the Score Cam Switches .

Check that 2-3 plays coil for resistance , it looks shorted even from down here. he.
You may not need that coil , If you can swap the adjustment plugs back to 1 coin 1 Credit.
You could swap out that coil or re wind it from a donor coil . If it is burnt out .

I would work through the relays . use a meter to check all switches, I found they were tricky to clean.
I hope some of this made sense to you .
Good luck . keep up the nice work. 4 stars!

Pacman , love this thread!

Regarding the 'non stop firing' problem .

I taken this pic of the 'Score cam motor ' on my Sega 'Jet Rocket' showing the solenoid plunger that sometimes jams and makes it continue to fire non stop ,
Only i cant quite see the set up on your "Killer Shark" , was wondering if it worked in the same way as jet Rocket?
Dose your game fire 3 shots at a time?
The jet rocket fires 3 shots with each press on the button. then the plunger should release.

Hope this can help out
Keep up the great work

score_cam_motor_(resized).jpg