If one is looking for reliable vintage CD players the ones to seek out are the Philips based players with the CDM "swing-arm" transports.
The Philips CDM transports are typically
far more reliable the Sony KSS transports.
Vintage Magnavox/Marantz/Philips all typically used the Philips CDM transports,among a few select others.
Sony mostly uses their KSS transports (obviously...) as do many other brands of CD players,Denon being among them.
Problem with the Sony KSS transports mostly relates to the lasers,and their tendency to die.
And many of the Sony replacment lasers are'nt available anymore,thus making a player using one little more than a paperweight when the laser dies.
Which is a d@mn shame because there are some
very nice CDP's that used those Sony KSS transports.
Anyhow JMO that this place >>>>
http://www.dutchaudioclassics.nl/ is probably one's best resource when shopping for vintage CDP's.
Beyond just which CDP's are reliable,then you get into other areas like the DAC(s) a given player uses and how those affect sound quality.
So that website helps fill in those blanks by listing DAC's and tranports given players use.
Just some food for thought.
HTH
Bret P.