Just a Quick one here .Picked up A SD40-2 seems to run jumpy and grinds ,so ITook out the gear box seems Iam missing 1 16T gear in the rear end .or is that it ? the last set of wheels spinn free. next is i have to turn up to 50 % to get her going some times , now the dealer sez '' they makem so fast these day's '' that is what you get. e- mailed Athearn about the gears ,nothing yet , any info would would help here . thanks much Tommy .