Vulcan speaks with sense here - it is most unlikely that your system has 2 pumps, though there are exceptions (my system has 3, but that's just being flash). As he (nearly) says, convection (not conduction) is driving some hot water around the system upstairs only. It happens because hot water is less dense than cold water so rises.
I am 95% certain that your pump has failed.
Holding your ear against a pump that is (purportedly) running and listening for vibration is not a good test - mainly pumps fail to rotate the impeller though electricity connected through the motor mechanism still makes it vibrate, even when it is doing nothing.
A fear its a plumber job unless you fancy getting your hands dirty. Make sure he fits a decent pump (Grundfos). Should be an easy job if there are lockshield valves on each side of the pump connections. New pumps cost about £60.