At the Sony service training a couple of years ago they said that in manufacturing their larger sets some small permanent magnets are installed in specific locations in the crt dependent on what part of the country the set is going to. A manual degausser is strong enough to demagnetize these, the built in degausser is not. The impression I got was that these are part of the CRT and not replaceable.
"Regarding surround sound, I know musicians too well to want them behind my back." -Walter Becker