I have a undermount soap dispenser that I THOUGHT were out of order - won't pump the land soap. Until I decided to take it apart and cleaned it. Then I filled the sink with water and tried it and it pumped fine. Went back to the soap - won't pump. Strange. I then filled the bottle with dish detergent, and it pumped fine. So the only difference is the soap which is thicker (more viscous). I thought high end soap dispenser (mine I think is a BrassTech cost like $68.00) should be able to pump thicker fluid even lotion. Strange.
MC