Do a voltage check at the video plug to make sure you have voltage for the blue, then follow it to the neckboard to see if you have it at the socket (Bk)....
Check color drive transisters Q302 Q312 Q322, Resistors R306 R316 R326 Also Zener diodes ZD301 Z311 ZD321, Also check for bad solder in all these areas
The connector wire from the board to the remote board has two broken wires inside the insulation,found this by doing a continuity check.The blue is back.Thanks for all your help modessitt.Ed