As far as i know there is no "belt" driving the clamper, it's a wire which i can't see how it can break.
Depending how your Beosound is oriented, having it at the bottom may be due to gravity or more likely a safety resting position. I think I've read something about that somewhere but can't remember where…
Most common fault on those things are laser failure. Maybe its just that and what you experience is a symptom of the whole unit being in a sort of degraded mode.
Maybe try to disconnect it, lay it flat, have it rest for a couple of minute and power it again with another CD in it. If it work but starts again to behave only after some time, chances are you'll need to change the laser. Depending on the MK of your unit it could be very easy or more complicated to fix, but not impossible.
If it's something else, I can't help…