watch very carefull during test. I bet one of the optos will go off normal plus intermittent once and awhile.
It confuses the computer where it is.

I cant say enough get the new Ingo clock board from German_pinball it is worth every penny.
Also ask him about his dmd-saver another great product.

Not to mention it streamlines the whole set up. It eliminates a board reduces heat greatly.

Stop ordering until you get ingos board. I got it with blue leds, cool white and the rgb so I can change them out (way easier on ingos board.
I also got the blue clock housing and white face from other people here on pinside. It looks and works flawless.

As far as your issue. Ingos board solves sooooo many issues.
Yours sounds like the issue of the optos being directly on the switch matrix. Ingos board solves that.
Make sure to get a dmd-saver also if he is shipping from Germany get all his awesome stuff.

Just dont lose the roll pin behind the clock hand. Put a towel down. It will save you a lot of time.

Very true its not the solution to everything but it rules out a lot.

The legs are fine as long as the hands can spin.
The clock error....did you swap the clock board at midnight.