Figured out the gong issue, and it was an easy fix! If anyone is having trouble :
Put it in solenoid test, and make sure the gong is unlatched. You should be able to push on it a bit, before you feel some spring resistance.
If you then latch the gong assembly, it should swing freely without any resistance.
When the gong latches into the swing through position, a coil pulls the plunger up, and the bell is caught on an armature attached to a trip coil. In this position, the gong will fully swing.
When it is in the kick back mode. the trip coil will un latch, and the plunger will push down into its stop, moving an arm behind the gong closer to the swinging target, causing the target to hit the arm, causing resistance instead of freely swinging.
The spot I marked with the arrows was very loose, and would slide back over and stick where even with the gong unlocked it still blocked it from swinging. Just adjusted it back to the right and seems to take care of it. Stern support asked not to tighten underneath for now, as moving it back over may from above may keep it from getting stuck again, may happen during shipping. 6 more games after and no issues, gong working perfectly!
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