cgallant wrote:
if you are unable to get the impeller off, then you will need to hold the shaft (generally the drive gear would have been enough. The impeller doesn't use much torque to tighten it, but it is usually installed with thread lock.

Thanks for the reply.

You're right, it had been 'secured' with an unholy amount of thread lock.

Some soft jaws in the vice and tiny blast on the impact gun had it off with everything undamaged - phew!

Thanks again,
Max