Quote: "When you move one wheel the wheel the other side moves in the opposite direction" but only half so when I move the right wheel the wheel the left moves in the opposite direction. but when I move the left wheel the big black cog turns and the right wheel stays still but if I move the left wheel and hold the big black cog still then the right wheel moves in the opposite direction. so the big black cog seems to be moving when I turn the left wheel, but stays still when I turn the right wheel. does this help??? also what difference does adjusting or buying a soft/med/hard spring on the big black cog???