The stem on the scissor arm is the same length as the stem on a candlestick - however, the stem on the scissor arm has a cap on the bottom - on a regular candlestick the stem is open, and the hookswitch goes on down into the base. So, the correct switch for the scissor stem would not have that extension on the bottom to mount to the bottom plate. I would post a picture of the correct switch, but I can't find one. Hope this makes sense.
Maybe someone out there has one of the scissor candlesticks, and can post a picture of the switch?