We have a Delta shower with single handle and spout. We have attempted to replace the valve cartridge and the spout. It's been a nightmare.

Where we are at now is that the valve cartridge is replaced. The spout pipe is the problem. The L shaped pipe that juts out of the wall for the spout to screw onto has come off. Its and L shape with about four inches of pipe each way. It isn't threaded. We have slotted it back on an we can run water through the spout. But, as soon as we use the diverter to switch to shower then the water pressure blows it back off. How do we fix it back on permanently?

On a side note we have discovered that the shut of valves for that shower/tub don't work. They handle and stems just spin. That's something we would really like to replace but the more pressing problem is not being able to use the shower.

The shower arm is suppose to have threads on both ends. The threads on the wall end must have broken off inside the ell fitting. There are a couple of ways to try to remove the threads. How far inside the wall is the ell?

That particular diverter spout has a set screw in the underside that must be tightened to attach it to the water line if it is the one I am thinking of, do you have the directions on the new spout to refer to?

the pipe pulls out of the wall and you are able to re-attach it but not in a permanant fashion?
so, is it a solder joint that has failed? is it new enough to have been a sharkbite joint?
poet a picture if you can't identify the pipe material..

for the shower head or the tub spout?

When you use the term "spout" I assume you mean the shower head and the shower arm has broken off where it attaches in the wall. You have to remove the remaining thread from the elbow. but it is NOT something everyone can do without causing further damage. Call a plumber who SHOULD have the proper tools to remove it and install a new shower arm.

I think you came closest. It could be that. The piece of pipe is in place right now. It has a piece of metal attached to the pipe with holes in that make it appear that it should be bolted to something. I'm thinking we should attach some wood to the wall behind the pipe and then brace the pipe. Or even a piece of wood underneath that that would prevent it from just blowing down.

Thanks to the other posters but it's not the shower head or anywhere near the shower. It's the diverter spout pipe.