MG Car Repair: MGB GT 1974 Relay fault, tracer wire, starter motor

Question
My dad's 1974 MGB GT would not start at all and he worked out it was the starting relay, when he replaced this the car indeed did now start but now on starting the car the starter motor keeps running after the initial start has been completed, the starter motor will keep going until you take off the power to it. it does not do this every time but enough to become annoying! obviously original Lucas parts are hard to come by so the modern day version of the relay has been fitted. Is the new version of the relay the problem or something else???
please help

Answer
Hi Matt,
You need to first remove the wires on the relay when it does it to see if the relay keeps it going. If it is the relay then you need to remove the wire on the relay that comes from the ignition switch to see if the ignition switch is at fault. Then test the solenoid you need to remove the small white w/red tracer wire from the solenoid to see if it stops. If it don't stop it, then the solenoid is at fault.
Howard