I mentioned this in passing a while ago, but perhaps I ought to make a thread about it here:

My first Game Boy brick from many, many years ago originally stopped working when the D-pad wore out. Basically, it lost its springiness - pressing any of the directions gave no feel of movement (though the game would still respond), and occasionally it would get stuck in one direction.

What exactly could the problem be? Is it just dirt, or would I need a replacement part? (Obviously to attempt any repairs I would need to get those security screws out first.)