I purchased a used Tamiya KT about two months ago. When I manually turn one of the drive sprockets, it doesn't matter which one, there is almost 1/4 of sprocket movement before the tracks start to move. Is this something I need to be concerned with? The gear boxes are lubed, this is a full option KT, and it doesn't seem to affect the running of the tank. In fact, it is a very smooth runner. Just more slop than my other Tamiya tanks.