I don't know if this will help but here is a link to the manufacturers website.
Powers: LM490/LM490-10 Series | HydroGuard Series LM490 Thermostatic Tempering Valves for Hot Water Heater & Multiple Lavatory Installations Over the course of time all tempering valves or anti scald valves seem to go bad and If you have well water, the guts inside the valve can get plugged up with crud and mineral deposits. That unit has unions on it so try shutting off the water, open up the hot and cold handles on a faucet to remove the pressure from the system, loosen the unions and remove the unit to inspect it. If the inside of the unit if filled with crud or mineral deposits. If it does, let it soak for a day in a container of white vinegar and see if that disolves any of the crap inside it. If it looks too bad you might think about swapping it out for a new one. I have well water and have had the pleasure of changing several tempering valves (Watts brand) in my house. I finally gave up and removed the valve and cut in a copper tee on the cold and hot water pipes and used a gate valve installed between the 2 tees to manually temper the water.