MG Car Repair: Starter motor wont disengage, brake master cylinder, starter solenoid

Question
 '77 MGB:  My starter motor won't disengage.  As soon as the key hits "run", the starter starts to crank the engine.  The only way I can disengage the starter is to detach one of the wires leading off the starter relay.  I've already replaced the starter relay...that didn't change anything.

 Any ideas?
Brad.

Answer
Brad, unplug the brake pressure warning switch from the bottom of the brake master cylinder. Then unplug the white W/red tracer double wire from the starter relay. Turn the key on and with a test light or volt meter test the double white w/Red wire you pulled off of the relay for power with just the key in the "On" position.
If the starter still activated in the run position even with the white w/red wires off the relay, you probably have the white w/brown and the white w/light green wires on the starter solenoid switched and on the wrong terminals.
Let me know,
Howard