Any suggestions as to what to do about the following would be gratefully
received:

The Honeywell 3 point valve's motor seems to have failed so I have
temporarily "fixed" this by wedging a matchstick in the manual lever so
it forces the HW and CH to be on. However, we do have a problem with the
shower on the 3rd floor which may or may not be coincidental. The HW
pressure on the shower (which is clearly pumped as one can hear the pump
come on and off when the shower is switched on), has become rather weak.
When the knob is turned to colder the pressure increases back to normal.
Over the last week or so, the pressure seems to have progressively
fallen further and further - not to a dribble, but not enough to sustain
a pressured jet for a shower.

The Potterton Suprima 80 boiler occasionally goes into red slow flash
mode, but this is always corrected by pressing the reset button on the
boiler.

Obviously the Honeywell valve (motor at least) needs replacing, but the
low pressure upstairs, and the incidence of the red light coming on in
the boiler suggests something more serious perhaps?

Many thanks in advance.

--
David Longley