Maybe posting a picture of the optos will help? Does the opto show open if you unplug it from the loom? If so the problem is most certainly at the opto.
I can't imagine a switch being installed for no reason. It may just activate a ramp almost make sound or something.
when plugged in shows open or beam not interrupted, when I unplug it shows closed or like I have broken the beam. Where does this leave me?
Btw it is showing correctly when plugged in but does not work when beam interrupted
