Hi Rick....Wayne @ Sew Busy here.... You could probably check your rudder/aileron mix to see if on Knife-Edge, with the rudder input, you have any roll coupling. If you do, it will adversely affect your rollers since you will either speed up or slow down the roll rate with rudder input.

So....the first place to start is to mix out the roll coupling (if any). Then, when practicing, you have to know what your airplane is going to do...that comes with "burning some gas"! Mark has always been a stickler for flying the plane at a constant speed, so you also need to pay close attention to this when you enter & throughout the entire roller maneuver.

I'm sure as soon as Mark gets the time, he will give you a bit more in-depth reasoning.
Wayne
Sew Busy
http://www.sewbusy.com