A cam disc (22) has a dual row of ratchet teeth (50, 52) on the periphery for dual rate of advancement by either of two oscillating motorized advance pawls (42, 54). The disc has alternating high and low concentric cam tracks (68) formed on one face. A plate (32) is registered on the cam disc hub (36) and has integrally formed plural resilient cam follower arms (70, 76) with each arm having a plastic cam track follower tip (72, 74, 78, 80) molded over the tip. The molded tips make contact with a stationary portion of the plate to limit follower travel when the cam is retracted by user movement of the shaft for setting the cam position. The high and low cam tracks engage adjacent follower arm pairs to effect a drop-to-make and drop-to-break action to each of a plurality of SPDT switches (38, 39) disposed for actuation by the cam followers.