you want to know how to degauss a tv this old? I did this w/ my ex-gf's tv (unfortunately it had been burnt for so long the color was lost in that spot, but its not green anymore!)
First, unplug the tv, let it sit for 3-4 minutes.
Next, turn the TV on its side and plug it back in.
Turn on the tv, maybe play something for 5-6 minutes.
Turn off the tv, and unplug it. Let it sit for another 3-4 minutes.
Turn the tv back to its original state and plug it back in.
Viola, instant degauss, well sorta.
This is a trick my bro got off a forum of shmups players (vertical shmups to be exact.) Works great, and fixes every problem I've seen so far.