Digital has come a long way since your Adcom. I'd say it's not worth repairing. Some specific suggestions for you:
Rotel RCD-1072 (see Absolute Sound review)
Rega Apollo (pushes your budget -- used around 700)
Cambridge Audio 640CV2
I have owned all of them. You might be able to get a new Rotel within your budget if the dealer is feeling friendly (and new is nice with CD players, due to moving parts). The Apollo is a little quirky in operation (takes about 12-15 seconds to "initialize" a CD), but most people get used to it. The Cambridge has the most forward, rock-n-roll sound.
FWIW, of those three, I still own the Rotel. The Apollo was a bit more musical, but the Rotel is, for me, more user-friendly.