Electrical gremlins

Good night...I believe I found the problem...After work yesterday I come home and took a look at the volrage regulator connector and the wiring on the fire wall....Come to find out the blue wire with the Fusible link attached came loose from the connector. I put it back in and started the car and no pop of the fuse and the charging voltage return to normal...Rev the engine...no pop....Didn't get to drive it because it started to get dark and my headlights are not working and getting ready to deal with this hurricane that's coming.....Question...What could I use to keep that wire from slipping out again?