Errr - wouldn't do this unless you had a sheet of plastic (think Fairy Liquid bottle) on either side of the connector body in the jaws of the vice, and ensuring that the connector is absolutely square to the vice jaws. Also, don't just wind the vice in tight at high speed: bring up the pressure slowly and try to "feel" for the point where compression has finished and the resistance to the jaw movement increases, signifying the crimp is complete.
If you do otherwise, it is remarkably easy to distort the shape of the connector, and it will simply fail to work.
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One of the few remaining Mk1 owners...
#00015