This article is from the RCA SelectaVision VideoDisc FAQ, by firstname.lastname@example.org (Tom Howe) with numerous contributions by others.
The only recommended way to clean a CED is to play the disc, and let the
stylus clean the groove. Removing the CED from the caddy and attempting
to use something like an audio LP brush on it will only make matters
worse. With extreme contamination, like a CED that has been immersed in
muddy water, the disc can be removed from the caddy and washed under tap
water, followed by a final rinse with distilled water and air drying.
For cleaning with the stylus, there are certain VideoDisc player models
that make cleaning the grooves easier. With the RCA SJT400 and SKT400,
the PAGE button on the remote control puts the player in page mode,
where it plays the same groove over and over. In this mode pressing the
NEXT button will advance the stylus forward one groove with each push of
the button. I use this technique to clear up skipping by putting the
player in page mode right before the start of the skipping, and
advancing the stylus through each contaminated groove in succession. The
alternative is to use the VISUAL REVERSE button to repeatedly play that
section until the skipping clears up.
Most Hitachi players (and their GEC McMichael and Sears counterparts)
can also be put in page mode by a technique not known to many owners of
these machines. Simultaneously pressing FORWARD NORMAL and REVERSE
NORMAL on the player during playback will put it in page mode, and then
repeatedly pressing these buttons will advance or reverse the stylus
groove-by-groove. Page mode is exited by pressing the PLAY button.