Hi!

Do you see these lines on everything you watch or just selected programming
from certain inputs? For example, is it there only on the tuner or is it on
everything?

What kind of a TV set is it? (Make/Model)

I'd start by looking for sources of electrical interference if all the
inputs on the set are equally affected. If that isn't the problem, check
your cables and playback devices. Your set's behavior doesn't necessarily
indicate that a failure is about to take place.

William