Last christmas I treated to myself to a dirt cheap 256MB mp3 player from Hong Kong for about 45 euros. (Less than 1/4 of what Irish retailers were charging for the same thing at the time, including postage). Its a nice little player, but like a lot of cheap electronic equipment it isn't the most resilient.
The other day I found that the headphone socket was opting out. Its a problem I previously had on a sturdy sony walkman I had for about 8 years. I think I paid 25 pounds at the time for what turned out to be an incredibly simple repair.
I opened up the case and found that there are 4 tiny contacts around the earphone socket, 3 of which had come away from their solder.
So I took out my soldering iron and soldered them back together. Put the walkman back together after the solder dried. And what do you know - problem fixed!