Hi I'm new here so hopefully this is the correct place for this question, if not I'm sure someone will give me a nudge in the right direction.

I've recently brought a CSI machine, all was well for a few weeks but today as soon as I press the start button the centrifuge spins. It will spin until the ball is lost then stop. As soon as the next ball is ejected it starts again. Diagnostics / switch test says " centrifuge enter last sw. #33 GRN-ORG / WHT-BRN"

I've exhausted my extensive knowledge. That means looked for any Green and Orange or White and Brown wires near the centrifuge and didn't find any. Knowledge exhausted!

I had a wild guess that it might be one of optical switches being activated and thinking a ball had entered but trying to make it think a ball had come out did nothing ( well actually I managed to make it spin even faster Doh!) I was wondering if one of the optical switches could have moved giving the impression a ball was permanently in the way but before I did anything stupid I thought I'd do something sensible and ask for advice.

Can anyone suggest what might cause this. Any help at all would be very much appreciated.

Thanks for your help guys. The screws that held the opto mount to the centrifuge top cover had worked loose. I tightened them and it works again. I hope any future issues are so easily resolved.