MG Car Repair: Key will not turn engine over, tracer wire, purple wire

Question
Have purchased 1974 MGB that has been stored for 11 years. Engine will turn over by hand, but cannot get it to turn over using the ignition. Starter and solonid are good. Will the seat relay or ignition / door relay keep engine from turning over ? Have power on the brown, white, white/green. Purple wire is disconnected but has power when test light is used and an alarm sounds, white/red has power when key is in start position and gray wire is dead.

Answer
Hi Tom,
On the starter relay is a yellow w/pink tracer wire on "W-1" pin. This is the trigger for the relay to operate. Apply power to that wire for the starter to operate. It comes from the sequential seat belt control unit. The seat belt and the seat switch do have inputs to the control unit. I don't have a test sequence for the control unit. The seat switch is just a two wire and the seat belt switch is just a two wire so each should be easy to test. If they are working you may have to bypass the control unit to get the relay to operate directly from the ignition switch, unless you are trying to get the car back to original.
Howard