A few years ago my parents had a similar problem with their BC2300, the glass doors where constantly open. Not such a good idea when having the player on it's stand, resulting in my parents knocking off the glass doors completetly...
So what I did, was to keep the BC2300 disconnected from the mains for a longer period (couple of days), and voila! When reconnected the doors functioned normally, and has done so ever since.
I did, clean the sensor area etc before, so the problem was not due to dust.
I know the BS9000 don't have the same automation opening the door, but the problem with the BC2300 was probably software related, and needed resetting. Might be worth a try before servicing it.
-Andreas
BLab5, BLab5000, BLab8000, BV10, BS9000, BS3, Beo5, Beo4, BLink1000, BLink5000, BLink7000, A2, A8, Form2