[modelman]

Rvjimd-I can see in the picture that the ring gear is not a precision gear and with it cast directly against the lower body that will cause a small problem. Is the ring gear out of round or is the problem holding the pinion in position. The O-ring idea could work but everything will have to be perfectly round and true to keep equal pressure on the gears for 360 degree swing. Keep working at it. I think you have done a great job in a short amount of time. Also I think making the tracks work is a great idea. To have all functions working on a model this small is quite an accomplishment.