www.pbfixit.com has an extensive series of photo-guides showing how to take apart and repair just about anything on any Powerbook made by Apple in the past 7 or 8 years. They also sell spare parts. Depending on what's wrong w/ it, you could have yourself a (relatively) new Powerbook for as little as $30-50 and some elbow grease. I'd go to your nearest Apple Store or dealer, get them to do a diagnosis and then buy the parts from pbfixit.com.

JD