Quoted from JustAl:
Anyone worked on replacing the balls on their Gottlieb Bank A Ball / similar? I found the Aussie(?) YT video showing how to pull the ball assembly off, but he doesn't actually replace a ball from the arm / pin it rides on. I don't want to assume that I can just squeeze the pin to remove the old ball arm (or can I?). I also have an arm without a ball. I do have new "balls on arms" from Steve @ PBR. Posted same on FB group EM Pinball, but no helpful responses (yet). Photos and/or video is super helpful if anyone has a reference. Thanks !
The ‘easiest’ way to install a new ball is to cut a slot out to allow the ball to slip around the switch bar. Tighten the switch bar if necessary. Follow the ball instructions to install the two rivets to lock it on.
In order to install like the factory did you would probably need nos switch bars as the old ones probably wouldn’t have enough meat to re-fasten.