Hello people! Mechanical engineer turned retro-CD-player-lover here. I have had some luck repairing a few units. Glad to help (albeit within my limited capabilities). Check the gear in my signature. Most of the devices there have been fixed to some extent and I might be able to answer a few questions. Cheers!
I love that retro-CD players are finally getting some love, I've got a DBX DB-5 on my main shelf that needs a belt. My buddy was looking for a player last year and ended up spending a decent amount, I was floored what they are going for now.
I have to admit that I am a cheap buyer, and most of my collection was once non-functional. Hence I have got some good deals (I paid 25€ for my D515). But yeah, I love seen this little nice pieces of technology resirfacing again, and I love even more the mentality at that time where manufacturers gave you the means to repair your stuff.