On Tue, 12 Feb 2019 07:18:07 -0800 (PST), wrote:

Out of the blue, my faithfull old Hoover washer tripped the RCD on my consumer unit.

After reset, it'll stay untripped when the machine is powered on at the socket, but as soon as I turn the control to anything other than 'off' the RCD trips.

snip

When mine was doing that it was carbon (brush) dust on / around the
motor and blowing it out with a compressor fixed it.

In our case it was tripping when power was supplied at the wall,
*even* if the machine was off.

Cheers, T i m