there are some pots inside the CD-Rom which my help turning it back to operation again.
maybe some other peeps here have more detailed infos about each of the pots adjustment.
and always remember, before touching any pot, mark their original position with a permanent marker, so that you always can go back to default.
only adjust one pot at the same time, and immediatly check the result/effect (-> better, worse, same).
only turn them slighlty (like 20 to 30 degree) per step -> not like the full range in one step.
hope that will help. good luck