You might want to get a thermometer and measure the temperature before tearing the water heater apart. The manual shows the standard thermostat has a fixed setting of 130 (F). There is an optional replacement set to 140 (F). If the measured temp is higher than 130, you might want to try replacing the thermostat/ECO assembly. There are 2; one for propane and the other for 120V AC operation. You only have to replace the one you're using.
If it's measured at 130 (F), maybe you have a problem with not getting enough cold water to the faucet that seems hot.