You won't find anything on NEC players of that era.I have an 810.I had to reverse engineer its schematic.Pretty intense ...
Yes it is heavier than most amps haha. think the servo needs adjustment, it takes a long time to play when i skip or select tracks
I bet the problem is fungus in the lens of the lens pickup. DUTCHAUDIOCLASSICS.NL says that the Nec CD-903 carry a KSS-123A laser pickup, and I've seen some KSS-123A with fungus in their lens. Clean it is not easy, but if you have skills, instrumental and patientcy, it can be done. Be carefull do not move the grating lens.
In this link there are some Nec CD players, there is a CD-810 that carries the same laser pickup.
http://sigechan-junk.sakura.ne.jp/page041.html
In this link there are some Nec CD players, there is a CD-810 that carries the same laser pickup.
http://sigechan-junk.sakura.ne.jp/page041.html