I got this pre-owned Sony 32" Trinitron. It's been working fine for a year except that last week i noticed that the picture has somehow dropped, ie 25% of the top screen is blank and I can't see the bottom 25%, like subtitles, etc. and also the picture is not a perfect rectangle anymore but a trapezoid (ie the upper border is shorter than the lower border.) I suspected that it had something to do with placing the center speaker directly on top of the TV because it I noticed it happening after i bought a center speaker and placed it on top of my TV. However, when I took out the speaker, the problem is still there. How can I fix this?