Dishwasher (Miele G638 plus) on the blink: gets to the
pump-out part of the cycle and sits running the drain pump
indefinitely (when I got to it this morning it was flashing
the "drain/inlet" warning light). It fills and empties out,
but it doesn't stop pumping when empty. I checked the
obvious bits (drain hose, non-return valve etc) but nothing
showed.

So now I've got the covers off and have extracted a thing
that I'd expect to be a pressure switch,
http://www.cyberpieces.com/devis/pieces-detachees-lavage-sechage-g636-0.htm
has an image of something with the same part number.

My questions a

* is it actually just a pressure switch (on/off), or have
these things got more sophisticated since I last fiddled?

* would one expect to be able switch it by blowing into it?
I've tried, and while something clearly moves inside,
there's no click, and the resistance between pairs of
terminals remains the same (infinite for most pin
combinations, short circuit for one). This fits with my
hypothesis that it's running the pump until the pressure
switch says it's empty, and that never happens, but I
can't see how to refute it.

* given that it appears to have adjusting screws (one is
visible in the centre of the image at the above link, the
other is in the tube at the very front of the picture),
can I simply fit a replacement, or will I have to adjust
it up to fill to the right level? I don't have a service
manual, so I don't know the procedure.

For completeness: the numbers printed in black round the
plastic part are 276974 E-01/09 T.NR.5380960 1200/700 and
embossed in the plastic are "Type 790", "83067", "8.8169",
"μ", "T85", and the terminals are numbered 12, 14, 11 and
the two gaps where terminals might be are both numbered 16.
I'm sure that's more info than could possibly be of use!

On-line spare parts suppliers in the UK don't seem to do
that exact part, but several offer
http://www.partmaster.co.uk/cgi-bin/...80&query=Miele G640&model=G640&path=67231,108720:128251
which looks very similar, but for a more recent model, so
I'll probably have to phone Miele on Monday.

Thanks,

--
Jón Fairbairn
http://www.chaos.org.uk/~jf/Stuff-I-dont-want.html (updated 2009-01-31)