Bleed nipples won't release - any tips?

[Gnasher]

Heat directed to the caliper to the area just below the bleeder is probably your best option. The heat gun would need have a fine point to direct it to the right place.

:agree


Heat the caliper body below the nipple at the same time, using a ring spanner or break nipple spanner, even a socket start to slowly apply pressure and undo the nipple, you don't need too much.  It's normally does the trick, but not always, sometimes the only way is to drill the bugger out, which isn't always cost effective as a replacement caliper can be cheaper then drilling and helicoiling, certainly quicker. 


Oh if you're doing it while the caliper is still on the bike, make sure you don't heat the break line