I don't know if we're talking about similar players here but my Yamaha 3
disc changer recently broke (door problem) and I was able to fix it myself.

The cd door is supposed to sit in a groove so the the cogs can drive it in
and out. However in mine it sat not in the correct groove but an adjacent
unused one. Hence "MECH " on the display.

I eventually got it out and re-placed the door and now it works fine. You
would need a decent set of small and medium screw drivers.

At a guess it would be a 1-2 hour job for a professional ( Me - 5 nights).
Hard to know if your problem is similar of course but it might be worth a
try to try and save up to $100


CP