I have a twenty-year old Sony Analog TV. Lately the picture expands and contracts by showing curved black areas on each side. Sometimes it stays with the black areas and sometimes goes back and forth from full screen to contracting continuously. Should I just recycle it or can it be adjusted? I don't see horizontal or vertical adjustments on the TV.
Thank you.

The width of the picture is dependent on the amplitude of the horizontal oscillator circuit. The height of the picture is dependent on the amplitude of the vertical oscillator circuit. The picture is formed by sweeping the screen using these two circuits. If the picture is expanding and contracting, the power level that is fed to these circuits is varying.

There are normally adjustments. If you don't see the adjustment knobs, maybe it's done in software. If it changes frequently, there's something failing in the power supply circuit.