Sketchy Physics wobbly joints

I’ve created a gear and rack that work together using sketchyphysics. I’ve made the gear a servo joint and the rack a slider joint. The problem is that if I move the control for the servo joint fast then the joints “wobble” and everything looks like it falls apart. (It all works fine if I move things slowly)

I’m using Sketchup Make 2016 and SketchyPhysics 3.7.1 and I’ve attached the file

Current grear and rack.skp (159.7 KB)

Hope you can help, google has failed me so far (or I’m looking for the wrong thing)