heater quit working

Water pump? I am not sure about the 1998, but my Corolla has no shut-off to heater core, it circulates all the time, but has a by-pass that somehow regulates how much coolant goes in to core. I have looked and can't find exactly how it works, and I'm not going to tear in to the under-dash to find out. But there should be two hoses going through firewall..not to be confused with A/C lines, they are steel. But maybe with engine running warm. heater on, very very carefully, no sleeves on, hold each hose in each hand and both hoses should be warm. If one is warm and the other not, it's not circulating...even if core is not clogged maybe, just maybe, the water pump is worn and the impellers are plastic and not pumping enough. All I can think of Brent. Good Luck..