On Aug 12, 5:31*pm, Peter Parry wrote:

If the fault is intermittent starting *I'd look first at the pump and
bearings - is it binding at all? *Induction motors have relatively
poor starting torque and a small obstruction can prevent them starting
reliably.

Well, thanks all - capacitor checked out fine, and I learnt why a
capacitor is used to run an induction motor - to create an offset
voltage so it knows which direction to twiddle!
I'd forgotten all about that...

Anyway, turns out to be stickyness - the cooling fan on the end was
running, so I pulled the fan back to where it looked like it used to
rest on the shaft, then it started leaking water.
An hour later, I'd taken the whole damn lot out, plumbed it straight
through, and without all the gubbins in the way, the water flow is
better anyway! (Still not quite pumped level, but perfectly
acceptable).

The whole thing was a complete bodge anyway - no idea who did it, but
it's gone now!

Thanks for all the help and advice.