Wards TV - cold starts fine; after warmup diff to shut off, won't turn back on

I have a 1988 Wards JSA12256 television that works fine from a cold start. You can easily turn it on and off initially, but after it warms up...when you turn it off, you can't turn it back on. It just clicks. If you select the ON click and wait, the set will eventually come on. It will restart if you let it cool down.