If the door is hanging low, it's either adjusted too low, or the hinges are worn out. My guess is the hinges are worn out. Open the door and try to lift it from the back end. If it lifts up and you can see slop in the lower hinge, then thats your problem. You can buy a new lower replacement hinge, and just buy a Dorman kit to put new bushings in the upper. Either way the door smacking the striker pin will eventually crack the striker out of the jamb.
