Sorry delayed reply due to new member not verified and unable to reply to hot topic even though I started it :/
This topic has turned into an interesting diabete about adding buttons when what I was checking was correct pin outs.
First let me say that I am repairing & preserving my table. As some of the previous owners have not been taking care of game.
I would NOT changing design/look or drilling holes (sacrilege).
Current plan to add credits to table by adding leaf switch to coin reject button. Using current coin door mechanism bolt. Did consider www.easycoinup.com, but this is permanent and harder to remove.