The shower valve behind this tile was not working. I twisted the handle for the hot water and it broke in my hand.
I entertained the idea of replacing the valve portion. Replacing the innards of old valves is a very reasonable thing to do. Upon closer inspection I discovered that the plumbing in the wall showed signs of leaking. I cut into the plaster and lath wall and discovered old galvanized pipe that needed to be replaced.
I went to the local plumbing store and bought a shower set and got busy replacing it. Cutting out old galvanized pipe is difficult even with proper tools.
I was happy knowing that I am upgrading the plumbing and will soon have a beautiful new shower set.
After spending most of my day I finally got the unit installed to discover one of the valve stems wasn't tapped from the factory. It wouldn't hold my fancy new handle. by this time it was too late to exchange it since the store was closed. I decided to simply tap new threads into it--my first error in judgement. I tapped the threads and my handle held perfectly in place. I turned the water pressure on and the valve no longer worked--in the on position. arrgh.. I took the the valve apart and found that I had broken it during the tapping process.
It was late and I was defeated. I shut off the hot water and called it a day hoping that the plumbing store was open on Saturday.