Hi Kickout.
Bowlers have an unusual config, compaired to pins.
Chk the 1st, 2nd shot, strike, spare components.
someone is not checkin in with the captain.
Those step units ALL have to talk with each other.
Even if you are not playin that game. on multi game bowlers i mean.
If you have gone through everything, you are about 1/3 done...
You WILL go through it again, and again, if necessary.
make sure you clean all the contacts with a dremel tool with a brass brush.
imho, files do more damage than good. unless they are very pitted, then, no option, except replacing.
Then, use an exacto knife to chk for loose contacts. the blade will cut into the side of the contact, and you can roll it around, if it is loose.
That is a big problem with these machines.
score motor switches are sooooo important too.
stick with it, and you will win.
Beer!