Horizontal lines, they can go away for awhile if we move the TV, but they come back. Most annoying. Can't figure out if there is such a thing as a "horizontal hold" button on this thing, but I think not. What do I do?

Hello

If your TV has nice thread like horizontal lines on the entire screen, at aboug 1 inch apart or so, it is due to the high screen voltage. In some sets, this voltage may go high due to a defect in screen control adjust preset, integrated to line output transformer [LOT].
You just open your tv and locate the screen adjust control. It can be seen on the above said LOT itself. There will be two adjustable controls, one for adjusting focus voltage, and the other for adjusting the screen voltage.
Dont touch the focus adjuster. The screen adjuster will be at the bottom of the focus control, and both of them have visual markings there stating 'Focus' and 'Screen'.
Just turn the screen adjust control a little, while looking the picture on the screen, and adjust it till the lines on your screen just disappears. Never turn more than this position. The turning must be counterclokwise, not clokwise, as this should shut of your TV.
Take every precautions when we works with an elelctrical equipment. As high as 25,000VDC points are there, while tv is working, you should be very cautious. Do this with confidence. Take care. OK.