Liftmaster cb24 with Chamberlain Photocells

[Sdunning]

Hi,
I have a dual gate liftmaster cb24 with 2 pairs of Chamberlain Photocells on the close. It has worked for about a year no problem, Recently the gates won't shut, the close photo flashes for a split second and stops them. I have checked all the wiring and it is fine. If I disconnect either pair, the gates close fine, it's only when both pairs are connected it doesn't close any thoughts?
Thank you

[Aiden Mitton]

Good morning,

Is it possible you could let me know how these photocells are wired (series or parallel) and where they're wired into on the CB24 control panel? If you could let me know the model of the photocells also that would be great.

Many Thanks,

Aiden.