Friends, I'm using a DC servor motor with an quadrature optical encoder on the back end of the motor shaft. Ran into a problem as the shaft from themotor that I have to work with has a tendency to settle into 6 positions in a revolution. The shaft will resist rotation initially when it is moved away from one of its 6 "comfort position" up until it is half way between the two "comfort positions". And then it accelerates the rotation to the second "comfort position". This is causing havoc when we try to run the motor at slow rate. Anybody has run into this problem? What's your solution? Do I have a solution other than replacing the motor? I'm not an expert on motors, so if anybody can explain to me what's causing this, it will be much appreciated. Thank you.