Ever since I moved into this house I have not been able to adjust the water temperature in the shower (luckily it was at a decent setting) and I am trying to figure out if it is a bad cartridge or potentially something else. It is a thermostatic valve, one handle that you turn that only changes (or supposed to change) the temperature while another handle adjusts the water flow.
I have pictures of the valve/cartridge below, I tried manually adjusting it with the screws on the right and left side of the valve but when I moved the hot screw closed to a good spot the water started making a whining noise so I had to back it out some more. Clearly this shouldn't be the proper way to adjust the temp since I have a knob that is supposed to do that.
I am completely ignorant when it comes to this aspect of plumbing and it appears that cartridges are a bit more expensive than a standard sink cartridge so I'd rather get some guidance before just trying something out.