Hi Agile - thanks for your help
Yes I have changed bled the pump, the rotor spins when turned with a screwdriver but not very smoothly. The resistance of the pump is also quite high. The pump's over 10 years old now.
If changing the head, will it need to be the exact same model?
Hi, want to change pump as very noisy and runs off balance, also hot water seems to take ages to heat up.
It's a Grundfos 15-50 pump
Is it possible to change the pump head by removing the allen screws? Will the new head seal ok after?