The pickguard on your Fender Precision bass protects the finish of your bass from scratches caused by heavy pick use. Over time, the pickguard on your Fender P bass may becomes scratched or the plastic might begin to crack. You don't need to take your Fender P bass to a guitar shop to have a new pickguard put on your bass. Here the steps you can take to make this minor repair yourself.
Place your Fender P bass on a flat, secure surface and loosen the strings. You can remove the strings from the tuning keys only, leaving them seated in the bridge if you plan to use the same strings, or you can remove the strings completely if you're going to put on new strings. If you leave the strings seated in the bridge, gather them and set them off to one side of your bass.
Remove the volume and tone knobs first. They pull right off. If they don't, insert the end of a flathead screwdriver underneath each knob and apply a gentle upward pressure. You don't need to worry about hurting the pickguard since you're replacing it. Next you'll remove the two screws from the pickups. There are two pickups, each with two screws, one on either side. If your Fender P bass still has its original thumb rest, remove that as well.
Set the volume and tone knobs and the thumb rest aside. You won't need to completely remove the pickups.
Use a small wrench to loosen the cord jack. Gently push the pickups out of their slots as you lift the pickguard away from your bass. The pickguard will come easily away from the cord jack and the pickups will remain in their seating chambers.
Put your new pickguard back on. Slip your fingers beneath the pickups and push them through the pickup slots. Ensure the pickguard seats correctly over the cord jack extension and it centers over the knob areas.
Put the screws back into the pickguard and tighten them down, taking care to screw them in straight. Alternate tightening the screws instead of fully tightening them one at a time.This helps seat the pickguard evenly.
Make sure the cord jack extends fully through the cord jack hole before you tighten it down.
Put the thumb rest back on, re-string your Fender P bass, and you're ready to play.
Take advantage of having the pickguard and knobs off your bass and give it a good polish.