Recording this for posterity, as I no longer own my S300:
- With both the S300 and your TV turned on, press and hold the "stop" and "muting" buttons on the front of the unit (not the remote control).
- Turn the volume knob at least 180 degrees. The Diagnostic menu will be displayed on the TV.
- Select the appropriate button number for "auto adjust".
- The unit basically does it all, asking you to select either a single layer or double layer disc. It opens the tray, asks you to put your disc in, and then calibrates it. I recommend calibrating a single layer disc first, then a dual-layer one.
This will help you eke out a little more life from your unit.