I have a ex16 and it does have a slight front back movement but turning the motor can change this, to little or alot, making this change makes the ex cut aggresive for thick fast cutting but less delicate cuts or not movement but slow cutting with very delicate cutting. I adjusted mine to have little as much blade movement as I can think i may need to check this adjustment, also the knob on the back of the ex once its set you shouldn't have to mess with it again it will also affect the blade movement to a point I have tested this.
