There are many features that alternate the white "Mystery Spot when Lit" lights.

On my game the top center bumper always alternates the lights.

The other three bumpers (left top, right top, lower center) alternate the mystery spot when they are unlit.

If those three bumpers are on (100 points when lit), they do not alternate the mystery spot lights.

Should ALL of the bumpers alternate the lights ALL of the time or is my machine working correctly as described? If not, I'd appreciate a hint. I have schematics but have trouble following them.

I have this schematic - does that work? Henry

CUE-T schematics copy.pdf

MarkG with the answer yet again! Thanks; every ten points was the answer and the game alternates lights as it should.