Hi,
Just had exactly the same problem with my 10 years old BS9000.
I fixed it by:
- downloading the service manual to get the exact test modes
- going into test mode
- selecting "Lightpen Out" (this moves the laser diode collimator/carriage in a more accessible position)
- cleaning the lens with isopropyl alcohol
Works now again as a charm
Note: despite what I read here and there on this forum, no problems whatsoever to run the test mode with a Beo4 (but I had to add SHIFT to the LIST)
Michel