I've had the switch stack and spoon out a couple times to clean and see what adjustment it needs. I did a little tweaking and so far it seems to be performing better. Time will tell.
As for the ball in play, I took apart the ball unit, scrubbed the ball unit contacts, mating arm and contact/arm near the center. It mostly fixed it. There were a couple times during game play it still didn't work, but I also scrubbed the switch in the game over relay (if I remember right) that feeds to the lights and it seems to be working better now. Jury still out if I have it working solid yet or not. Feeling like there's still something loose, but the more I play it and it consistently works right, the more confident I am that it's working right.
Thanks for the heads up on the Double Bonus. It's now working, probably because I have the ball in play now displaying.
Still watching for other function issues. I've noticed it's hard to hit the captive balls hard enough to make it to the Special targets. I might need to tighten up the flipper EOS switches to see if that helps.
Thanks for the compliments on this game! This game actually doesn't belong to me; I'm just doing all the refurb work. It's going to be a gift for a friend; his first game after wanting one for a long time. His wife asked me to find a game for him, and this one was a great fit. The plastics are original but were warped a bit. I cleaned them up and flattened them between glass in an oven. I really wanted to repaint the cabinet, but stencils aren't currently available and the condition isn't all that bad. Pinball Pimp would be willing to model a stencil off mine, but I didn't want to pony up the cash for a game that had decent artwork already. There is paint missing near the flipper buttons, but the rest is mostly in good shape. I'll patch in some paint to hide the worn areas. New Titan silicone bands throughout, Comet warm white clear LEDs, new pop bumper parts (including the mushroom bumpers) and all new flipper parts. Fixed a few minor playfield wear spots. Scrubbed the coin door, plunger, new legs, etc... The back glass was surprisingly flawless. It's coming together and getting close to being done.