GI - Could be as simple as a fuse - There will be a informational card in the backbox denoting the GI fuses. Check them all.
So – tell me.
These games use 5 fuses for the GI ???
It appears that 5 x 5A Slo Blo’s are required for the GI ??
So – if ONE of the 5 is out , then 95% of the GI could be out ??
Each GI string is seperately fused ie lower playfield,left playfield etc. Check for 6 volts at header pins J120, J121 and isolate fault to wiring or PCB. Check connectors as most are burnt out. PM me if you need further help.