I just finished building this set, and when I was done, I realized the wheels were reversed: when going forward, the rear wheels would go forward, but the front would go backward. I looked up a bunch of places, and they said one of the differentials needed to be reversed. I double-checked the book, and they are both in their correct locations. The rear differential gear mirrors the front differential. Meaning the front differential gear is on the left side of the car, and the rear...