Dratted pump is seldom used in my coupe, and the little brass impeller gets corroded and stuck to the plate at the bottom, then no workie. I have four or five spare pumps and when it's time for my yearly safety check (without which I can't renew registration), I swap until I find one that works.
Last time, the pump ran but no water...? The hose was kinked under the reservoir. Thanks Murphy for tossing me an easy one.