To force the pin out you need to disassemble the wing as much as you can so that you can avoid damaging parts by keeping them out of the way.
1. Remove the screws from the back of the wing and slide it out:
2. You should end up with the back like this:
3. Now this is the very hard part. I will provide pics for reference but you basically have to follow the same instructions I provided for Thunderwing here in order to remove the pin.
Be concision that it's not easy to remove pins but it's doable.
Once you remove the pin, add a very thin coat of super glue or nail polish, doesn't have to be on the whole pin just half of it would be good and will make it easier to reinsert. Allow it to dry, reinsert it (this should be much easier than removing it) and the added thickness should provide the friction you require to keep the wing in place.
Good luck but remember to be careful not just with the toy but your person too.