Lee: Possible cure for front wheels jumping track at switch points. Check that ther flange of the wheel on the inside of the cirve isn't hitting the tip of the point that's open. After years of getting pounded by locos hitting the curve, the older style Gargraves, the type without what appears to be cast points, tends to have the points spread apart slightly. It appears to me that the rail appears to cant outwards. Can take some tricky bending so as not to pop the rivet.
If anyone know how to rebuild Gargraves switches to have the new type points, I'd love to hear how.