I bought a beautiful Nikkormat, black, and it looks and acts like brand new. But...

one of the the back door hinges is corroded and 'gone'. The back closes perfectly and there does not seem to be anything loose. However, it would not take much to loosen that back as the only intact hinge is the upper one.

This hinge is held together by a metal pin. I have other Nikkormat backs from my parts stock, though not quite as new and pristine. If I do decide to change the backs does the pin punch out easily? Is there something that I should know beforehand? Thank you. - David Lyga