That's the kiddie, the female part which grips the pins of the male part lose their springiness over time, and it causes arcing within plug.
I have done two like this including my own, connectors cheap as well, I used AMP connectors as this is what the sensors use on the cossies, about £4/5 total, solder them on and them tie wrap so don't move, keeping as much of the METAL SHEILDING of the original wire as possible on the sensor side.
I don't know for sure it is this because I am not there, listen for PUMP PRIME first as this will tell you if it is getting a signal or not, mine started by buggering about and losing power going all flat performance wise, and I found it by chance doing the "WIGGLE TEST".
tabetha