Turned the TV on and had sound but no picture. When connected to cable box, get a squiggly green line that looks like a smile. With no cable, nothing but static sound. Tried switching inputs, but since can't see screen, can't tell if it is actually switching. Manufactured in July 1998. Any ideas?

So when you connect a cable box to it, you get a wavy green line on the screen?

Honestly, a TV that old is going to be pretty expensive to fix, and once the part that is bad now is fixed, who knows what will be next. Chances are you'll end up dumping tons of money into it. Absolute minimum is going to be around $150-200 to have someone come out and take a look at it and possibly fix it. But if any part has to be replaced, you'll be looking at a bit more than that and another part could fail in a couple months.

My suggestion is that it does not sound like your lamp, and is going to get expensive trying to fix it. Invest the repair costs into a new TV.