You should be able to move whatever it attached to the valve with little effort. You won't be able to move the part that is attached to the sway bar.

The valve is aluminum so heating it might not be a good idea. It might be a better idea to just get a different valve. If it's frozen it might be hard to make it work properly again. If it snapped in motion it could have done damage inside the valve. You'd have to pull it off and tear it apart. If you want a different one let me know I have some spares.

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