I use a foam swab, which come in a DeOxit Survival Kit, to clean the laser lenses. These are available for sale separately as well and don't leave any dust or fibers behind. Use a decent quality photographic lens cleaner, safe for plastic polycarbonate lenses for best result. You must be sure that the cleaner will not harm the laser lens or degrade the adhesive that holds the lens to the lens holder frame, if it's mounted that way.
Pioneer CD players are notorious for the lens's falling out and rattling around in the case.This renders an otherwise operational unit DOA. I've bought and fixed more than a few Pioneer players with the loose lens rattling around inside the case and returned them to 100% operational again.
DO NOT USE Cyanoacrylate (Crazy Glue), as even a pins-head amount can melt the plastic lens or cloud it from the vapors in close proximity to the lens while wet. I use a 2 part epoxy, less than 1/2 of a pinpoint amount in the lens groove, well spread and thin as possible. It doesn't take anything much to keep the lens in place, as it doesn't need to be structurally sound or take a lot of stress. Just enough to secure it is more than enough.
Recapping really old higher quality CD players can improve tracking ability and even sound quality big time. By old, meaning 30+ years old, and sometimes younger. The units which use the first generation Phillips CDM1 transport often have big time tracking / playing issues with old-failing caps. Many instances the transport is wrongly condemned, and new replacements have long since been discontinued. It only takes 1 bad cap in the CD transport/servo control to cause mistracking, distortion errors, or a player that wont read any disc at all. New PS, servo, and audio caps will often return the unit to full operation, and even improve sound quality over the old caps, even better than when the caps were still fairly new. It seems Phillips with all their resources didn't always use the best quality caps even in the high end CD players.
I've had dead CD players here where the soundstage was very narrow, 1 dimensional and fixed centered between the speakers. Upon replacing old aluminum electrolytic caps, installing Nichicon Audio Grade, Fine Gold or better, of the same rating, the soundstage opened up, extending beyond the speaker planes in all directions while displaying very noticeable improvement in overall separation. Some folks will roll in better modern DAC's as well, provided there is a higher quality modern equivalent available. I've personally replaced the old 4066 chips in some of my Sony cassette players and was able to attain an immediate, not so subtle improvement in sound quality. I'd say anything with the old 4066 chips could benefit from adding a socket and rolling in newer 4066 substitutions with better specifications.
If you have a CD player with 10v caps in it, I always upgrade them to 16v of the same farad rating. My experiences with 10v aluminum electrolytic caps in audio gear has shown me these fail more often than caps of other voltages. Anything with 10v caps I open up are replaced with 16v caps automatically. YRMV, and YMMV of course.
