take it to jeweller he will put it in an ultrasonic bath for a small fee it uses sound waves to clean it and free it and no damage

mm
August 2013

First try rotating it as you try to release it.
It sounds as though it has dug into the pin and made a ridge.
If there is room push it further up the pin to expose the ridge then gently file the ridge down with a nail file

GB in Wales
September 2012