That would be a 1993 Zenith tv set. 25" or 27" size?
If it is 25" or 27" the washed out picture is more than likely the
picture tube. Zenith had a very poor reliability on picture tubes
between 1993 and 1997 in those sizes.

The line across the top of the tube is an obvious one for any tech.
A vertical circuit malfunction, usually caused by one or more high esr
capacitors.

The picture jumping when the cabinet is tapped is also an obvious one,
a bad solder connection in the set. Depending on exactly what happens,
how it jumps and other symptoms, will determine where to start.

Before wasting any time on it, check the picture tube on the tube
checker.