There is no such thing as a "weak firing pin", it is struck by the hammer driven by the mainspring. The first thing to try is tightening the "strain screw". This is located on the front strap of the grip frame near the toe of the grip frame. You may have to remove the stocks if the gun has target stocks. Tighten the strain screw firmly, if this doesn't solve the problem come back and we will make other suggestions, but odds are this will be the cure.

__________________
Gunsmithing since 1961