I have exactly the same problem, and I have performed exactly the same trouble shooting tests.
This is what happens additionally for me, I hear the machine makes a noise, but nothing happens, i.e. it does not drain. If I then open the coin trap so that water is drained from there, eventually the pump starts to pump out water with good speed.
So, it is not clear to me that the pump should be the problem, since when it runs, it runs very nice..
Any other idea? If the original poster would post if a pump change indeed helped, it would be very appreciated.