Westclox SPUR alarm clock silencer button placements

This picture compares the post WWII alarm silencer button location on Westclox Spur alarm clocks (and probably other models using the Series 66 dual-ke movement). The beige clock on the left, from 1954, shows the button protruding from the back, mounted integral with th movement and suspended by the front and rear movement plates. The black clock on the right from 1940 shows the pre-WWII style, with the alarm silencer button mounted on the top rear of the case, independent of the movement. Both served the same purpose of silencing the alarm by blocking the movement of the alarm striker arm. The only other mechanical difference in the two versions seems to be the needed addition of a small protrusion of the alarm striker of the pre-war version to align with the silencer button.