You have to use loads of WD-40.
or better still WURTH 2040 release oil is the buisness.
you might need a pair of vice grips depending on how tight it is.
and just work back and forward for what seems like an eternity use plenty of release oil when working it will clean out the rust mostly
using firm pressure it will eventually start to go free then kinda force it a little more and you should get it free. it usually takes ages.
you can also spray it in the hole and leave it for a couple hours and repeat the process until you get results.
Hope this helps m8.
