There is a red LED that indicates the player does not recognize the disc is there
Just throwing this out there, but is the disk a normal one and not a cd-r or SACD ?
If you plan on keeping the player, have you thought or tried to contact Sony ?
I'm with Elevick; it's truly not worth trying to repair it. And I seriously doubt there are many older CD players that are "collector's items". Maybe a California Audio Labs Tempest, but that's pushing it.
My advice is to simply replace it with a used Sony, Denon, Music Hall, NAD, Jolida, Rotel or the like that's a more recent vintage. I think you're going to see a very significant improvement in the sound.
Some, if not all, CD players from that era typically do not recognize the first and last track of modern CD's. Try selecting Track 2 and see if that works.
As others have stated, a 25 year old CD player really doesn't have any intrinsic value regardless of its pristine condition.
Digital to Analog (DAC) technology has improved tremendously. The DAC used in the CDP 701ES can't compare to even mid-range CD players manufactured today, in terms of audio reproduction.