Shower diverter
There are two areas in your bathtub spout that can corrode and impact the diverter's function. The threads on the screw that connects the pipe to the spout can corrode or crack, and the spout's finish can corrode, flake off, and cause blockages. In severe cases, if such damage is left untreated and you continually attempt to use your shower or tub, water can trickle along the pipe and saturate the inside of the wall.
If the shower faucet diverter is stuck because the washers are old and have broken or the plastic valve diverter inside the pipe has broken, then it is time to replace the faucet itself. The diverter is not an overly expensive mechanism to buy and replacing it may be easier than attempting to fix it.
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