Abstract: The assembly, in a first embodiment thereof, comprises an annular cam retainer which rotatably journalled on the mortise cylinder of an exit alarm unit, and has a limb disposed for movement by the tailpiece of the mortise cylinder for engagement with a bearing surface on the rotary, switch cam of the assembly. The cam retainer retains the rotary, switch cam in an alarm-silenced position while the key may be rotated in its key cylinder to a disengageable position and removed. The modification kit comprises a cam retainer (i.e., an unthreaded annulus, in one embodiment) required for modifying a key-operated, exit alarm, switch cam assembly to enable removal of the key with the alarm in a silenced position as aforesaid. The modification method sets forth the precedural steps in retrofitting a switch cam assembly with such a modification kit.