Signs of low water pressure include less water coming ... and do the same for the shower valves behind the cartridge. You'll need to remove the cartridge to access the valves.

It’s a good idea to familiarize yourself with how the valve type operates and make sure it turns smoothly. If it’s stiff or corroded, you may need to ... turn off the water pressure.

The water might be coming from the temperature and pressure relief valve (T&P valve), though. To make sure the drain valve is ...