I can't speak to the KSS-150A from direct experience, but after working on a lot of vintage CD players with Sony KSS pickups, it is my (admittedly non-scientifically arrived at) conclusion that some just don't age gracefully, while others seem to remain rock solid for much longer than they have a right to (under heavy use). I've observed this in a number of models of player from around 1985/86, using various KSS-12x pickup types. Some seem to have been poor designs (or at least subject to a relatively shortened service life, for whatever underlying reason) so I surmise there are likely other pickup types that are similarly marginal after ~40 years in the field.
The problem is that except for anecdotal information developed in threads like this one, no one has really quantified an actual list of pickups with a high failure rate, so far as I'm aware. The only pickup I'd say is widely known to be a bad bet at this age are the various interations of the Toshiba/Olympus TAOHS-L pickup block used in many models from 1982-85 or so.
Of course, we are also seeing failures of servo and tracking circuits now, due to aged components drifting or outright failing. That will impact the quality of the laser "lock" onto the disc data even if the pickup itself is still at or near 100%. There is a greater observable incidence of failed caps, transistors and even IC's on many players that are now 30+ years old.
To get one in that age range now that works as is, is an increasingly unlikely (and lucky) turn of events. I've had a few players that needed extensive recapping, some other passives replaced and even some transistors and IC's changed out to restore proper function. Most of these were found to be working again with their original pickups, after the above referenced work had been done.
