Old tv only shows half picture

Question

10 years ? old 20" diag. toshiba tv (glass picture tube ?) has started showing only the top half of the picture.
There is a bright line separating the picture top and the "blacked-out" bottom --- it does not "float" --- and it is happening on all channels.
I read one of your other answers and thought you needed that info ...

Is this a problem worth trying to fix? --- I can't afford one of these newer tv's right now but I could put a little ! bit of money into this one if I could get a few more years from it. Please help!