thought that would get your attention! 
One of the bleed nipples on my Princess calipers leaks like home office secret report.... 
Tried replacing the nipple but it is obviously something to do with the caliper.
Any clues ?
I thought maybe the face that the nipple seats onto may be damaged. Is there anyway to fix it?
Cheers
For those who only came along for the 'dodgy' title ... All I can offer is a few minutes oggling my current avatar....
I see no reason why you can't reface it so long as you pop out the piston first.
I still remember going to ford and without thinking asking for some bleeding nipples!
the look it got
Odds somebody has damaged the seating drilling a seized or brocken nipple out, only doge I can suggest is using short set screw with a copper washer under the head.
yeah thats a point, have you inspected the bottom of the hole to see it's condition?
are you able to examine the conical seat in the caliper - could be some grot in there.
not sure if you could reface it but what about fiting a ball bearing and a brake pipe fitting; as you do it up, the ball bearing closes the hole in
the brake pipe fitting (would work best, if at all with the seat in good shape so may not work.)
the copper washere and bolt would work but bleeding it will be messy 
Not inspected it yet, was too disheartened and just gave up the other night!
I will be inspecting asa best I can. I just hoped there was a special tool for refacing them or something......
But would a bolt and washer setup get through SVA ?
www.classicbrakes.co.uk will recon them for £130 the pair incl Vat.
Ed.
May be possible to use BTs idea but fit a bleed nipple to the bolt ?
Cracked caliper due to overtightening nipple ?
Sorted well I hope so - it looks OK
I ground the end of a drill bit to 45 degrees and used it by hand to clean up the mating face. refitted the nipple and it seems to seal - but
haven't put 'foot' pressure on the pedal yet - just by hand.......
I had thought of sending them to c lassic brakes but their site seems to be down....?
Cheers