Our mixing valve in the shower has stopped mixing. It is in the picture below. The water is tepid regardless of the position of the handle. Are there problems that a homeowner can fix?

Also, how do I begin to disassemble it? The set screw seen in the picture comes out easily, but even with it out, nothing untwists or slides. The wall is completely finished on the other side. Any suggestions on how to begin at least assessing what the problem is would be greatly appreciated.

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  • If yanking on it doesn’t help, try dribbling some clr limescale remover into any part you can. Once apart, you might find that scale is the root of your problem. Feb 6, 2023 at 0:22

2 Answers 2


Start with trying to tighten the small hex screw on the handle, maybe it is just not preventing the handle from freely turning around without actually moving the valve shaft.

You could also unscrew it and pull the handle and try to operate the valve with pliers. That will tell you if you have to go deeper and disassemble more.

  • I'm not able to pull the handle off. It doesn't budge even with the set screw out.
    – Wynne
    Feb 6, 2023 at 1:23
  • @Wynne there is evidance of heavy clack deposits, remove that with vinegar
    – Traveler
    Feb 6, 2023 at 3:17
  • Thank you, Ruskes - I was able to pop it off! I'm not sure what to do next so I'll make another post.
    – Wynne
    Feb 6, 2023 at 4:04
  • It definitely looks like it should come out. It's probably jammed because of deposits or rust. It's not clear but the whole assembly may come off the base, so lever it there gently with a flat screwdriver or a blunt knife. Just keep wiggling it slowly.

  • Sometimes, the base plate is just a cover and will come off. Try twisting it first and if it moves then try gently prying it off.

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