On Sun, 10 Nov 2019 14:12:40 +0000, Jeff Layman
wrote:

snip

Yes, that could be it. But it would have to be pretty early on in the
circuitry, as it still trips when the on-off push switch is "out".

If not before the switch, I wonder it's only a single pole switch as
if it was (I'm not sure if it's 'allowed' to be) it could still be a
neutral to earth leak past it?

I
guess it could just be a "false" physical break, and it's really an
electronic circuit break which still leaves some connection even after
switching off. It might be obvious when I have a look inside.

In our case is was carbon buildup on the (WM) motor brushes causing a
N-E leak (and would trip the RCD with the power switched off at the
socket but on on the WM).

It may be time for a new drier, but I'm intrigued as to what this one is
doing.

Can you measure resistance (when unplugged) from live to earth and

That was one thing I was going to try, but I wondered if it might need a
decent voltage (although not quite up to Megger standard!) to see if
there was any breakdown.

I think our fault was quite measurable with my DMM and was seen to be
cleared once I'd brushed / blown all the carbon out. The WM then
carried on until the main bearing went again.

Cheers, T i m