Hehe, you lot must surely be tired of hearing about combi problems by
now, but here goes:

I've got a Vokéra Maxin 24E, which, as far as I can tell, was
manufactured sometime during the stone age (I'm almost surprised it
doesn't have chisel marks on it).

However, I've clung to it lovingly over the years as it's proven to be
superbly reliable, bar one thermistor change I did last year.

Just recently it's stopped delivering hot water. Here are the
symptoms:

-Turn hot tap on, nothing happens at the boiler (no fan, solonoids or
anything are actuated).
-Turn all hot taps in the house on, and it fires up fine, hot water is
produced. I can reduce the flow by turning the other taps off and it
carries on heating and everyone is happy.

But I know very little about the insides of a combi, beyond the basics
(hot water heated via CH circuit and diverter valve). What the vacuum
pipe does and how the flow is detected is a mystery, though some
background reading on this group leads me to believe that it could be:

-Split diaphragm (if my boiler has one)
-Duff microswitch
-Sticky mechanism to microswitch

So, first off, does anyone know whether this boiler has a diapraghm or
not, and if it does, how would I identify it in the boiler?

Presumably if I follow the cold water in, it should be one of the first
components in the system before the heat exchanger?

Regards,

Tony