Not saying I don't believe you, but having had little experience with drip coffee makers since ~2010 when I lost my last one, I simply can't imagine the design involved that would let coffee get into pumping area (worst was that you accidentally spilled ground coffee into water tank.
Can you point to some examples? Just so I can share what to avoid :O
The specific mechanism that gums up the works occurs at 6:45. When you raise the lid of the modern version, grounds and coffee bits that have dusted up to the lid of the coffee maker drip via condensation into rear water reservoir.
For greater detail, juxtapose minutes 8-11 with minutes 16-21.
Mr. Coffee represents the king of drip still. And it is the greatest contributor to this fundamental design flaw (imp).
Can you point to some examples? Just so I can share what to avoid :O