There is a single original pine floorboard in my upstairs hallway that squeaks loudly every time someone steps within three feet of it. It sits right outside the main bathroom door. I finally decided to fix it on Sunday afternoon.
I watched a video about driving special breakaway screws straight through the face of the wood into the floor joist below. I ordered the screws. I mapped out exactly where the joist was supposed to be by tapping on the floor with the heavy plastic handle of a screwdriver. It sounded solid. I drilled a small pilot hole. I drove the first screw in and snapped the metal head off exactly like the instructions told me to.
I stood up and put my full weight on the board. It shrieked noticeably louder than before.
I thought I might have missed the center of the beam. I tried putting a second screw two inches to the left. That one missed the joist completely. It went straight through the subfloor into the open ceiling cavity below. Now I have a floorboard that squeaks loudly and has two bright metal dots permanently embedded in the middle of the wood grain.
I refused to put a third hole in the wood. I dragged a heavy wool runner rug out of the spare bedroom and threw it right over the spot. You can still hear the squeak perfectly through the wool. I just step completely over the rug when I walk down the hall now.