The painting/weathering was well done. I liked the dust effects.
Things to improve:
1. The jerry-can should have a handle. Very difficult to use otherwise
2. The tracks. The surfaces of the tracks that rub against the ground or the wheels should be polished metal. All of those surfaces, not small scratches. The inside of the track also gets polished by the rubber on the wheels (unless it is a rubber surface). The guide teeth also get polished in a uniform way. If the rubber on the wheels can reach all the way to the base of the guide teeth then they should be polished metal all the way. The polished area depends on the shape/profile of the tooth and the wheel and rubber so each combination of wheels and track will behave differently.
3. Sprocket wheel. All the polished areas should be the same size and shape. The teeth go into the holes in the track links and get polished in the same uniform way. The surface of the idler, if it is not covered by rubber, would also get polished by the track.
4. The fenders. Should be horizontal unless they have been damaged somehow. Could have gotten pushed upwards by something so this is just a minor point.
These are things that would be noticed and judged at contests
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/ Robin