A surgical instrument having a handle, elongate shaft and end effector has a drive shaft to operate said end effector. The drive shaft has a proximal component 310. A trigger mechanism 22 mounted on the handle has a pair of contiguous apertures 318 having a first and second size, such that the proximal component 310 may be inserted through the larger aperture then moved to be held by the smaller aperture. Proximal component 310 may have distal and proximal flanges 802which are larger than the smaller aperture. A slot 311 through the proximal component 310 receives the drive shaft. Movement of the trigger mechanism 22 causes longitudinal movement of the drive shaft to operate the end effector, which may be jaw members having electrodes.
