The timer on my combi-boiler is not a digital display - it's an old
mechanical dial. There are four 'triggers' (2 on - 2 off) around the
dial so I can set the heating to to come on twice (if selected) in any
24hr period.

When it's time for the heating to come on the dial (which up until
this point has kept time fine) gets stuck - as though the triggers
themselves are preventing the dial moving on into the change of state.
If I apply a bit of pressure to turn the dial, once it clicks past the
trigger the heating comes on fine - it just needs to be forced. But
this obviously defeats the object of a timer (I could just as easily
switch the heating on/off using the 24hr setting).

We'll be moving out of the house over the coming months (so
suggestions of getting myself a modern boiler will be politely
ignored....), but until then, I'm not sure how much more whinging I
can put up with from my girlfriend when the heating hasn't come on in
the morning.

It's a Worcester 9.24.

If anybody knows of anything that may be worth trying on the boiler
I'd be very grateful - otherwise I'll be tempted to apply for that
"Wife Swap" tv program.

Cheers