Give Oppo a call or send them an email. They may be able to walk you through a procedure to fix the tray. A long time ago I had a similar problem and they were able to resolve it on the phone. If not, remember that Oppo has a flat rate repair policy. I don't know what it is right now for the 983 but should be around $60.
Thanks for the info. I sent Oppo an e-mail and they said the 983 has an alignment error and that I should turn the player off after removing any disc and then lift the front of the player several inches and then drop it to try and bring it back into alignment. I guess I'll give it a try tomorrow. Can't hurt.