I have had my pump cover lose it's connenction three times. Each time I turned the screw another quarter turn and now it seems to be holding. I finally figured out that if you tighten the locknut to far, it will atually pull the allen screw away from the pump wire, even if you don't allow the allen screw to turn while your tightening the locknut. My advice if i was doing it again would be to turn the allen screw just far enough to light a tester with the key on. Then finger tighten the locknut. Finally turn the allen screw another half turn, which will solidify the connection and lock down the locknut securely.
Good luck!