I always found it interesting that Gottlieb officially called this feature a "swinging target", whereas Willams called it a "spinner" because Williams had a different feature they called a "swinging target". That swinging target was found on machines like Heat Wave, Riverboat, Swinger/Funfest, etc and basically consisted of a standup target that used a motor to oscillate the target back & forth, thus requiring shot timing to hit it.

I got started with Williams EM machines and recall being very puzzled the first few times I heard someone refer to a (Gottlieb) swinging target because I couldn't find anything resembling what I was picturing in my mind from my Williams machines.