Sony CDP-CX300 skipping - terrible skipping problem solved
(modified post repeated for clarity)
I applied gun oil (a thin oil that says it has silicone in it) with a Q-tip to the single metal laser guide rail. That eliminated the skipping problem. Such a simple fix: remove the cover, dab a small amount of oil on the rail. Amazing that something that simple solved the skipping problem. I had observed that CDs always started skipping between 4.18 and 4:54 minutes. That was an indicator of a "location problem".
Detail: Remove the cover. Visually look for the metal guide rail (shaft). It is located at the rear left of the player (where the laser movement mechanisms are located) when looking from the front, and is seen in between the black plastic. The laser mechanism slides on it and this can be observed by powering the unit, selecting a disk, then increasing & decreasing track numbers on a rotating disk - the laser will slide on the rail. Now, reach into the access to the metal guide rail with a Q-tip moderately saturated with oil (3 in 1, gun oil in my case), and wipe along the accessible surface of the metal guide rail surface; the "backside" of the rail opposite the access area cannot be be reached for lubrication without further disassembly. But reach around "behind" the rail as far as practical. This lubrication task is very easy to accomplish and should have been included in the manual.
I had previously done some disassembly and cleaned the black "split drive rack"(gear), then re-lubed it with white lithium grease. [The pinion gear (not seen) and rack move the laser on the metal guide rail]. This lubrication did not solve the skipping problem.
These players are not sold any more, but it sure is convenient to load up as many as 300CDs - and avoid e-wasting an otherwise useful CD player.