Northwestern Gumball Machine

I bought this machine at a classic car auction in the memorabilia section. The push lever was sticking when I put the penny in so I thought I would take it apart to clean it. Duh, dumb mistake. Anyway I am hoping someone can help me out. There is a spring tension lever (attached to the main parts, that fits into the coin slot. It (I'm guessing) triggers the mechanism to allow the knob to be turned to get the gumballs out. Can anyone tell me where it fits into.
The screw that holds the turn-knob on the rod is very rusty & I don't want to try & remove it as it might break. If I could I would be able to get the machine totally apart & probably figure it all out. I will do that if no one can help.