Code:
http://www.pacificsites.com/~alanjudd/920.htm
Here's a guide to replace the battery in General Instrument/Motorola receivers. These receivers, especially the 920's, are all getting old, and the batteries are starting to fail. If the battery voltage drops too low, the unit ID number will be lost during a power failure. If the unit ID number is lost, the receiver will no longer be able to be activated for subscription services, and there's no way to restore the ID short of replacing the motherboard. I believe the receiver will also stop receiving fixed-key DCII channels as well.

The batteries are fairly cheap and the procedure isn't difficult if you're handy with a soldering iron.