The door striker is the metal u shaped latch that is mounted to the body of the car. That the door latches onto when it is shut.Or that holds it shut.You should see to Torxes screws loosen then up slightly and tap it in a hair.Then tighten the screws and see if it is any better.
Just to inform you that I wasn't able to unscrew the door striker yet. The torx screws were too tight. In the sense that I had to use the electric-power drill. In any case, the screw heads gave way and I need to get a new set.