
Ok I removed the water pump and checked the impeller which seemed ok and rotating with a bit of resistanc. I then went back and checked the new fuse and it had blown!Any ideas what to do next??
Did you try and run it in air or under water. If it ran in air it will have drawn too much current (needs resistance of water to limit motor speed) and possibly blown fuse.
I would suggest using a continuity tester to check that power from the tap micro switch is reaching the connector block at the tank after you have put a new fuse in to check the circuit is sound and doesn’t blow the fuse.
Then you reconnect pump, submerge in water and operate the tap quickly, you should hear pump working as it primes.
If nothing either impeller is still seized enough to stop motor rotating freely.
If fuse still working, have another go at pushing on the impeller to reseat and see if the resistance to turning has reduced.
If the fuse has gone immediately after you switched the tap on for a second or so you have an electrical short to earth after the connector block at the rear tank. The only item after the connector block is the pump, so you have to conclude that the pump motor has shorted out giving the high current draw that is blowing the fuse.