Someone please move this to the Restoration Society. I don't know how the hell Buying and Selling got clicked.
I'd like for this thread to be for general Dreamcast troubleshooting. Why? Because I have been troubleshooting like a madman for weeks now! Here are some general things I've found that don't seem to be mentioned elsewhere.
Why is my Dreamcast occasionally making a grinding noise when the disc is being read or when I open the lid?
Cause of problem is likely the threading piece attached to the laser and its white plastic contact point. Best way to solve this is two undo the two screws holding the white piece of plastic down and then replacing it.
(Pics to follow if people need them)
Why does my Dreamcast occasionally read discs fine but other times skip during music or not play certain music CD's or specific games?
From my experience this is just a faulty laser. If you can fight your way to the laser mechanism you can replace it without any soldering.
(Pics and links to help videos to follow if anyone wants them)
Other problems, like the controller board F1 problem, have been explained pretty well before. If anyone else has any general troubleshooting tips, especially for weird problems, post in here. There's a good chance I'll update this post in the future for everyone's benefit, if anyone sees it necessary.