|HP Laserjet P1102 paper tray front view|
Try taking a look at the paper tray (pictured above). You may notice the tray's not even. One side is slightly higher than the other. Here's a view from the access door after you remove the toner.
|View from printer toner area|
A small object managed to get stuck under the tray and that's causing the loud noise. The printer's trying to push down the tray but the object is preventing that hence the gears make a loud grinding noise.
What you need to do in this case is to slowly turn the metal shaft the pickup roller is attached to backwards so that the white tabs on either side aren't pressing the tray. Be careful when doing this because you may twist the metal shaft in the process and that can cause other problems.
Once you manage to give the tray some space to lift upwards, you can try shaking the printer so that the object goes to one side.
Here's a sample of what you might find under the tray.
|Hmm... how did that coin get stuck there?|
|Nice and flat paper tray. As it should be.|