What I learned from this progress is that having the arm come in from one end only is extremely unstable. Even at a perfect fit the thing is wobbly. What I realize is that the arm should extend the entire length through another hole on the opposite side. The cam or whatever gear can then rest in the middle. Without equal distribution of weight it's difficult to make it do what I want.
I'll drill a hole on the other side, run the arm through, have the cam sit in the middle and then drop another dowel from the top. From what it sounds like I have to add a wheel of sorts to the bottom of the dowel to move smoothly against the cam. We'll see though.
In other news, I'd like top pick up a wood burning kit with letters so I can burn letters into this thing.