Moen tub spouts install on the end of your tub pipe, which comes out of the shower wall. Moen tub spouts slide onto this pipe and secure with an Allen screw, similar to the way your faucet handle is attached to the cartridge. Replacing the spout upgrades your bathroom and it is a good way to fix the diverter, since this part is inside the spout. All you need is an Allen wrench to complete this fast, and easy bathroom home repair.
Turn the water supply off.
Find the set screw under the faucet. On many Moen tub spouts this screw is located inside of a diveted or embossed section of the spout underneath the main body, nearest the shower wall.
Take this screw out with an Allen wrench. Pull the spout off by hand. It should come off fairly easily, if not try unscrewing the set screw a little more, it might be rubbing against the pipe.
Flip over the new spout. Make sure the set screw is already inside the mounting hole. If not, put it in there and give it a turn or two, just enough to hold the screw inside. You do not want the tip of the screw sticking up through the bottom of the spout, it prevents the spout from sliding onto the pipe.
Place the tub spout onto the pipe and firmly press it back against the wall.
Tighten the screw to finish installing the Moen tub spout.