http://www.facebook.com/photo.php?fbid=1814901450418&set=a.1101810303585.2017707.1176526713I have a shower/bath combo. There are three knobs on the wall, one for hot, one for cold and one to pull and force the water up to the shower head. When you try to turn on the shower head, nothing happens. Took the knob off and the casing and tried pulling the brass piece... finally turn and came out completely in my hand. Do I have to open up the wall behind the shower and completely remove and replace?

Show us a pic. Problem is more likely in shower head.

Still waiting for a picture. Sounds like you pulled the diverter apart, they are easily repaird if we can dteremine the brand of valve.

http://www.facebook.com/photo.php?pid=32220681&l=2ced062b16&id=1176526713
Hope it works this time.

Shower head is fine. It's the shower diverter. Just have to figure out how to get it off with an 1" and a half of plaster between it and the tile.

You need a set of tub faucet wrenches or sockets. When looking in hole the first nut you see is the bonnet nut. That and the packing around the stem prevent water from coming out around stem. The second, larger nut you see is the shoulders of the stem body. That's the one you want to remove. If the faucet socket is not long enough, fit two together. One socket will fit inside another to extend the length. Available at Lowe's, Home Depot and hardware stores

So... I figured it out. It is a Kohler diverter... was finally able to narrow it down. I couldn't find one at my local box store and the plumbing supply isn't open until Tuesday so I moved the rubber washer down and used the parts I had to turn the shower on 100% of the time until I am able to track a diverter down. Worst case scenerio I can order a diverter online and have it by Wednesday. Thanks for the help.