Here is a pic of my replay stepper, but the same applies to the ball count unit. The screw that is circled should not be cranked down too tight. That pivot arm needs to be able to move. Back the screw out a little and tighten the nut while holding the screw. A small dab of Super Lube would help also.
Make sure the gear is pushed forward all the way before tightening the spider arm.
Try using Noxon brass cleaner for the contacts points. A drop on a micro fiber cloth will polish those up nicely. No sanding necessary.
Here's a pic is my ball count unit contact plate after polishing.

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