I’m certainly not an expert, but I’ve read dozens of newsgroup posts and all of them said that there is usually a thermistor in the degauss circuit that must be cooled off before the degausser will activate when powering up. Regardless, the TV consistently becomes badly discolored whenever I use the discrete On code and I hear the "boing" sound.

Anyway, are you thinking that dust in the TV may have become magnetized or something? It's hard for me to imagine that that's the problem, but who knows?