A couple of questions about impulse flippers...
1. Aside from Williams, were there other manufacturers that featured them on their machines? I believe I recall that Genco had them, but don't know for sure.
2. Are all impulse flippers operated by pressing either flipper button or are there some machines with impulse flippers that are independently operated by separate buttons?
3. When did Williams' impulse flippers finally disappear? Clay mentions on his pinrepair site that they went away in mid-1955 (i.e., "Luckily by mid-1955, Williams had sobered up and replaced the impulse flipper with a standard Gottlieb-style flipper design," http://www.pinrepair.com/wmswood/), but which machine was the last to have them (or which was the first not to have them)?
Below are the machines that ipdb lists as being produced by Williams in 1955:
1955-03 Peter Pan
1955-03 Race the Clock
1955-04 Poker Alley
1955-05 Band Wagon
1955-05 Smoke Signal
1955-05 Three Deuces
1955-08 Can Can
1955-08 Circus Wagon
There is a youtube video of Smoke Signal (May 1955 production) that gives the impression that it had non-impulse flippers (and they're independently operated by separate buttons), but it's hard to know whether or not the machine was retrofitted with them.