The_kid is exactly right. I owned a GCD-575 that had the same problem you're having, and when I opened it up the switch contacted were bent and corroded. After 15 years and numerous moves, it was no surprise. I was able to clean them and get the drawer to stay open again, but it had also started to have trouble reading discs, so I decided it was time for a new player. I got an Onix XCD-88, which was an amazing improvement over the Adcom.
If you have to pay a tech to fix it, I'd suggest you put the money towards a replacement.
If you have to pay a tech to fix it, I'd suggest you put the money towards a replacement.