I am a keen audio enthusiast and also have soem hi end audio equipment and elite laserdisk player.
I know the exact item in question.
I have tried the Green pen technique and it does work but dependent on your system and observation.
To an enthusiast there is change in the sound and some in the picture.
To a person not used to modding i would say that they wouldnt realise much change.
I have tried many mods to both Ld and Cd players.
I had some cds frozen and they sounded very good.
One good mod is to use blue tack underneath the LD player so it is stable on a platform etc.
Just 4 blobs of blue tack on the feet can make a huge difference.
In theory the green pen should refract any red laser thats bouncing of the cd surface as the laser hits it.
Red being opposite on the colour wheel to green,or so the theory goes.
Laserdisk players also make great cd transports as the mechanisms are overly engineered for smaller disks.
Also removing the transformer out of most hi fi and externally using it will improve matters.
Thanks,
Ian(uk).