[david2000]

hi steven
it looks like the video unit is at fault if you could borrow a video unit to try to see if that is the fault or what you could try is take the blue connector off the video unit then take the blue cover off the connector then using a voltage meter test that there is voltage going to the WRY WIRE white red yellow and to the gk wire GREEN PINK pin 1 and pin 3 if my memory serves me right try this to see what happens
all the best david