Help - my shower is squealing also. But I don't think it has anything to do with the shower head. It more seems to be coming from the supplier pipe. And it only does it when it's hot water. You can change the tone of the squeal as you adjust the knob for water temperature. This drives us crazy in the morning. If we turn it off and back on again we can usually continue without the noise, but it seems to be doing it more lately. Any easy-fix thoughts?

Hi suebdo and welcome to The Plumbing Page on AMHD.
You piggybacked on a 5 year old dead thread so I gave you one of your own. Before you post look in the upper left hand corner for the date.. Sounds like you have a piece of trash caught in the hot water supply that's vibrating when you run the valve.
Shut the water off and open up the valve. Remove the cartridge and inspect the inlet ports, Now turn the water back on for a few seconds to flush out the supplies and open valve body. Reassemble and test. Noise all gone now? Good luck, Tom