The Audio Research CD players starting with the CD3 use variations of the Philips CDM Pro2 drive mechanism. This is the same drive mechanism in CD jukeboxes so complete drives as well as parts are readily available.
So I wouldn't worry that much about buying a CD3 mk2. If you can push it you might consider a Ref CD7. The price of these has really dropped. And they are a truly amazing analog sounding CD player.