Thanks for the replies, I'll take a look on the rear of the controller for any foreign objects, the controller is housed within a IP rated housing but you never know what has managed to creep its way in.
Controller: BFT Rigel 5
Single leaf, BFT LUX 2B
Thanks
Dave
Recently started having issues with it tripping the RCD when the gate is closing, only appears to happen when the temperature outside is above 15 degC (never happens on a cold day) I've replaced the RCD with no luck, motor capacitor has been tested and is all gd. Photocells have been inspected...