Quoted from t2:
There are holes in the bottom of the turbo blade that the optos shine through. The turbo blade does not always stop in the right position for the optos to shine through the hole, therefore, the opto doesn't register. If you lock the 1st ball it will get shot out. If you then lock the 2nd ball it will get shot out but will start the 2 ball multi ball by kicking the 2nd ball out of the ball trough.
So, basically, after the turbo blade spins and comes to a rest the holes in the blade do not line up with the optos so then the opto is reading closed. Opto is working. I can manually move the turbo blade so the hole in the blade lines up with the opto then it will read open.
I checked my turbo and it does not stop with the opto lined up, it stops every time with the opto blocked which lines up the pocket for the ball to land after being shot up by the VUK.
So what you are saying is, when the green arrow lock light is flashing, and you try and lock the ball, it shoots it out and will not hold it? When this happens, does the first green arrow go lit solid (indicates a locked ball)?