There's a key underneath the boiler which can be turned to increase the
water pressure - this has worked fine for years. After I last had the
boiler serviced (British Gas on their cheap service deal) I noticed that the
key had gone. The engineer was a bit of a bozo and I thought no more about
it, assuming that a screwdriver would function just as well.
The pressure needs increasing - using a screwdriver I can turn the valve
and hear water flowing but the pressure indicator stays the same. Have I