Have you repaired a Sega Saturn? Leave any info you've learned!

Round and oval button saturn models have interchangable laser assemblies.

It's possible for the hub to get pushed down too far on the shaft (no disc in drive error) or possibly pulled up (The cd won't spin). I got a used saturn where the hub was down far enough that the cd was scraping and couldn't be read. A gentle upwards pull ws all it took to get it working again. WARNING: the hub is usually firmly affixed to the shaft and in the right position. You should only attempt to move it if it is obviosly out of position.