TD4 rear bleed nipple help!

Trying to bleed the brakes on a TD4. Front no probs but got the rear l/h and it won't budge. Took the wheel off to get better access but it's starting to round off so soaked in wd40 and left it for the moment. Sure I saw a thread on this a while ago but can't find it. Anyone got any advise to get this off or a link to a previous thread?? Also is there a part no for the bleed nipple/can I get a replacement? If it rounds off completely what are my options?
Cheers

use a hex socket to slacken ,you can also loosen by tapping end to relax thread ,good pair of vice grips ,i use extracor socket that bite s harder the more you turn if its snaps new cylinder if you get it out rtc1115 is no for new screw

I couldn't get a socket on there as it was to close to the pipe so using open ended spanner, maybe this is where I'm going wrong? Have ordered a couple of new nipples as I'm sure to round them both off!! will try giving it a tap on the end first as already tried shocking the spanner

If the bleed nipples have seized to the extent that you are rounding them off the best option, in my opinion, would be to fit a pair of new rear wheel cylinders, if you try to drill them out (after you break them off) without stripping them down the swarf will almost certainly knacker the seals.

Sorted, plenty of wd, a few taps and a bit of luck

with your new bleed nipples jobs good for a few more years