Got the HO2 error on my (5 yr old?) Panasonic S35 DVD player tonight. Followed the instructions on this site and fixed it! It's easy to take the lid off (5 screws). Once you do that, plug it in, open the tray with the remote, put in a DVD,close the tray, and then give the white plastic wheel on the top a gentle little nudge to get the disc spinning.
(Yes - the HO2 message means the disc isn't spinning -it's not about the lens or the laser - you can tell that's the case, by the way, because the rotational position of the DVD will never change as it goes in and out, even though the graphic on the screen (next to the "READ" lights) implies the dvd is spinning...)
chris h. (milwaukee), May 2009