the Bs9000 has CD orientation springs that need to be set correctly for the current orientation. Look through the service manual and you'll find the info, make sure you have it set correctly before you do anything else. While you're at it, you can get into test mode and see what errors are displayed. 

Subamgis wrote:

Dad found a Beosound 9000 MkIII that was handed down to us from some rich relatives of ours.

It seems like everything but the CD player works. When I try switching CDs with the glass cover down (while the thing is laying on the table), the CD player gets caught and stops for a moment before trying again, and then stops again. It doesn't get caught when the glass cover is up.

When I try playing a CD, the CD doesn't spin, and the thing reads 0:00. When I spin the CD with my finger, then it tries to spin it but only slowly and then stops. Probably a bad motor or belt.

Found the service manual but can't find the relevant parts.

Everything else works fine, the LED panel, the AM/FM radio, etc.

Not sure if I should try to service it myself or just knock down the price.

It needs correct adjusting of cd transport, it is in the service manual. Just 2 screws on back that need to be pointing the correct way. After that, it most likely needs a new laser, and since it is a MK3, the only way is by getting one from B&O, which is kind of expensive.

No belts or anything needs fixing(maybe the belt for the glass-lid motor, but that has nothing to do with playing cd's)

/Weebyx

Subamgis wrote:

When I try playing a CD, the CD doesn't spin, and the thing reads 0:00. When I spin the CD with my finger, then it tries to spin it but only slowly and then stops. Probably a bad motor or belt.

Very same symptoms here (MKII) so I will be following that thread! But I've got a lot more issues to fix before.