After serious thinking The Natural Philosopher wrote :

Leaving it plugged in to the same socked with no changes at the CU
disconnecting the heater and running it for an hour did'nt trip.
So, can I be confident its the heater elements? or, could this just reduce
the load
when in fact it could be the combination of the motor etc ??

sadly yes.

Leakage can add up, yes.


Disconnect the lot, and put a resistance meter between heating coils and
earth., There should be NO detectable resistance there. If there is its
definitely new coil time. If there isn't, sadly it doesn't rule them out,
because they might short only when hot.

Or it might be more susceptible under pressure of mains voltage - which
is where a megger comes in.

What about the insulation supporting the heater coils, any signs of
burnt on carbonised fluff? If they are pot (??) it should be possible
to clean them. Not suggesting it would work, but might carburreter
(sp?) cleaner not be effective in cleaning this off?

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk