Years ago I installed the excellent SACD upgrades from Vacuum State
During this period I was able to repair some of these players with new Lasers & Spindle motors from Sony. These parts are for the most part no longer available, Some new lasers may still be available on ebay at a price.
New Spindle Motors which spin the discs are not available. However recently (Nov’23) I had an enquiry which got me thinking. I have a couple of old motors which failed due to bearing wear. Specifically the thrust plate sapphire bearing wears causing friction & also disc to laser gap to be reduced. On the motor shaft is a ruby hemisphere which causes the sapphire wear but the ruby is hard enough to remain OK.
I worked out how to remove the sapphire and after some web searching I managed to get a few sapphires of the required size. Fitted one and the spindle spins like new. I think its good a new. Sent it to owner to fit and waiting for news.
Of course the player might still not work due to laser issue or other problem.