Hi Trevor, I did remove the link bar on Saturday and moved the sensor arm back fully and the lights moved down to the correct position,I then pushed it forward and they went up again.
The problem seems to be when the link is attached the sensor points them too high.
For now I have left the link off and wired the arm back to keep them down.
Do you think they need calibrating to the correct height or I thought maybe the sensor arm may be able to be removed from sensor body, moved back then 're attached to the body leaving it in the correct position?
Thanks for your help so far.