Ash,
before you swap with Davids M/C...............try the broom stick method.
trust me it works ..............
wedge a broom stick/ long length of steel onto the brake pedal so that the pedal is under constant pressure (hard) & leave it over night,
this will probably solve the problem , basically it gets rid of all the tiniest air bubbles back to the M/c.
on the race bikes we used to use a cable tie on the front brake lever overnight, hey presto.....brakes that would work & have a "nice feel" to them.
Try it, nothing to lose, don,t even need to get the spanners out
cheers
andy