Maybe a stupid remark…..did u measure the secondary voltages? Is your game maybe jumpered for 220-240V operation??

There should be a connector at the tramsformer panel with just jumper wires. Gottlieb delivered for each voltage a jumper with specific wire colors. Blue and green are for 220VAC 240VAC operation (correct me if my memory is failing in this). They used orange also if I am correct. You can compare it with your working game.

Why doing the groundmod in system 3 games? Gottlieb used decent connectors in system 3. Groundmod is not needed.

I know the groundmod myths already and I just strongly disagree to perform them in sytem 3 games. We are running a >100 game collection, from which many Gottliebs, I am also a volunteer in a pinball repairshop 1 day in a week. I never saw a system 3 game having problems with grounds. System 80 games do and also those in which groundmods were already performed but in such a way they are causing more problems then solving them. But of course....everyone can work on their machines in the way they want. I do it my way (and don't follow the hurd….better to think by yourself from time to time as I learned as a technician/engineer).