Hello folks. This shower was actively being used when this valve started to become unpredictable. It would not reliably change the water temperature and those using it would resort to quickly turning it left and right to try and get it to “catch” and change the temperature.
I would like to either swap this valve out with a new one or fix it. We’re fairly handy but this is a new area for us. I do not have experience soldering but am considering converting to pex for this short section. I’m looking for this groups feedback on either approach. Note that while I don’t have from the other side of the wall, that location is in a hallway closet and I plan to cut an access panel in there for this project.
Thanks!

Use Apollo brand. Use the Apollo crimping tool: https://www.homedepot.com/p/Apollo-1-2-in-and-3-4-in-PEX-B-Crimp-Tool-69PTKH0014C/301573902#overlay
I bought the tool, used it about ten times and then returned it for a refund. Just be careful with the packaging.
Those can be impossible to get into tight spots, which is why the cinch clamps have become more popular. If it’s a concealed area, I’ll use 2 cinches or a sharkbite if I can’t solder a converter in.