1996 Pontiac Grand Am Fuse box problem

Hi, I am having a problem with my fuse box. I have electricity in my car but the gauges and the lights for the dashboard don't work so I cant tell how fast I am going or how much gas I have in my car nor any other light on the dash. Everything else is fine with the power to the car. I checked the fuses but all of them are fine I even changed one of the 10 fuses and the power went back on but it still doesn't work. I don't know what to do. what could be the problem? Is the fuse box loose? sometimes I would have to tap the bottom of the dash to get the lights and power to the dash to work, but it does't work still.