Are the taps 10 years old?
Do they have flexible connectors from copper to tap /and are they stright or kinked in any way? Has the problem of lack of flow got worse over the years?
Taps old? Er, this one is fairly new but was like this from the start.
Flexi connectors are "slightly" kinked but I'd be suprised if they where restrictive as a result.

Not got worse over time as such, just got worse when the pump was fitted.
Just checked...
...flexis are not quite straight, so I checked further, with tap open.
It flowed the moment I moved the flexi pipe. Its not twisted or kinked.
While holding the flexi...
Tap opened, you can feel the pressure move the pipe, but the tap doesn't flow. Wiggle the pipe further, tap flows. You can see the water (via surface tension) in the tap opening move as you move the flexi. All while tap is open. If moving the pipe to cause the water to withdraw it won't flow, obviously, but move the flexi in a way that makes the water drip extend from the tap enough, its millimetres, and the pump kicks in and it flows.
Interesting. Pressure clearly there, and overcoming the one way valve ad I can feal it at the flexi. But still won't flow. Jiggle flexi and it flows. Surely the pressure is more force than jiggling as far as the tap is concerned...?
