Have you got a bulb/circuit/voltage tester?
heres a highly technical drawing of the terminal, check your getting power from all the terminals, i cant remember which way round they are but the two +'s are for the main & dipped beams with the other being a common ground - all you can really do now is start there and work back til you find it and hope you dont end up at the fusebox, car electrics are a real pain in the rr's
