No. The metal unit fits exactly the same as the plastic unit. The sodering was nice and clean also. The only other thing I noticed was that the gears turned more easliy on one side. The other side seemed a little stiff. The two sides sounded different to. The gears on one side seemed to rev up real fast while the other side sound like it was grinding a bit. I don't know how that would affect the signal to cause a delayed response.

I checked the spin on the plastic gear box and both sides acted the same.