Honestly, there is no way I would have been able to understand how they work without working with them powered up. Many times I'll need to twist and old lamp socket to get it working and bright. Not sure how that would be done working with the game off. Worst shock I've had while working on pins is when my body hit a flipper button while I was touching a flipper coil. What's strange is that sometimes when I get a jolt, it will causes me to laugh.

I'd avoid touching the transformer, fuses and larger coil that might get activated.