there is a bit of play in all coil machines & the stealth with a arcing motion, the bishop and neotat are truly linear as they go up n down with the clip.try to not run the needle so straight up/down. Your hand has learned to work with the arcing motion so its like retraining your small motors skills to a new motion. I think its better if a person sticks to one style of machine (give -no give ,linear,swash etc and just let the art flow instead of constantly trying to adapt to new machines.