14 day skipper not advancing on Intermatic sprinkler timer
The brass pins have a particular tab positioned to trip the actual switch that controls current to the valves. The silver pin they refer to has a different tab to drive the skipper wheel. They are not interchangeable. If you are missing the silver one, you need to procure another one and install it as directed.

If you cannot procure one, it might be possible to fabricate one based on the brass pattern. The only difference is probably the tab position. You will have to deduce somehow what proper tab position and shape that it would take to drive the skipper wheel. There is likely some protrusion under the skipper wheel that engages this tab, much like how the switch engages the brass tabs, except at a different position relative to the clock wheel.