The people above are right, it was easily cured.
TVs back then didn't have degaussing coils built in, which is why it didn't go back to normal like the monitor someone described.
However, using the same magnet carefully it would be possible to demagnetise (or at least adequately remove the magnetism you imparted) on the mask of the TV by simply using the opposite end of the magnet to the one you used on each patch (the method speedevil mentions will probably work also).
I have done this to many CRTs with an assortment of magnets.
(Me, I'm not... in any way intoxicated, Wed 21 Sep 2011, 18:58, Reply)