I've been working on a mechanism for a pull toy to drive the legs of a tortoise back and forth (driven by the green axle in attached .zip file). When I click the red rod and drag it in Model view, the mechanism works as it should - the big wheel rotates and drives the lever back and forth using the slotted arm. But once I try to animate it or make a Basic Motion study, the closest I can get it to working as it should makes everything spin properly for a second, then the motor flips in the other direction (I have it set to Constant Speed, not Oscillate) and the slotted arm flies off the mechanism (see attached .gif for demo of the dragging + animation attempt.
I noticed the Gravity was facing upward and I figured that might have something to do with it, but reversing it just messes up the animation more. I've tried just about every setting that I know of, including making the 3D Contact Resolution, Geometry Accuracy, and frame rate much higher. You'd think with such a simple mechanism it'd be easier to animate, but I'm at my wit's end! Any suggestions would be greatly appreciated, thank you!
Using 2019 Solidworks Student Edition.