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!

#2 is the most sage advice!
I watched a friend drop a screw right down the drain. Then we found out that it wasn’t ferromagnetic (the hard way, LOL).
I will never forget gettingan old, proprietary screw machined for an bath tap fitting after losing it down the drain…
Fortunately p-traps are there and should be (yea, right) removable.
But yea, whole lot better to just not let it happen. BTDT, got the badge.