Stepper Motor Twitching

Hi, I have a Sanguinololu 1.3a 1284p with stepsticks installed that I'm trying to use to control a Zen Toolworks 7x7 mini cnc machine. Currently I'm using replicatorg with this profile to test the motors.

My problem is whenever I have a motor plugged into the X or Y axes and use replicatorg's manual controls to move the motors they kind of jerk and twitch in random directions with random intensities ranging from barely noticeable to ~10 degrees.

Even if the motor is plugged into the x axis on the board, pressing jog x or jog y in either the positive or negative direction will make the that motor plugged into the x axis twitch. This also is true if that motor is plugged into the y axis.

Right now I only have one motor cable, I could make more if it might give somebody more information about this problem.

When any of my motors is plugged into the z axis they work perfectly.

One click to the jog x or jog y controls will make the motors twitch once.

When I hit the jog x or y buttons a whole bunch and the motors are twitching for a long period the step sticks don't heat up

My motors are 6 pin, but in theory they should work with 4 wires. I don't think this is the problem as the z axis will move any of the 6 pin motors just fine.

Things I have done to try to diagnose or fix this problem:
Changing the pot on top of the stepsticks. This slightly increased the intensity of the twitching.
Moving the step sticks to see if one is broken. This changed nothing.
Changing the wiring on the motors. All this did was make the Z axis not work either, so I switched them back.
Using a different firmware. I have tried Marlin and Sprinter, neither of them have changed the situation.

I think the problem may be with the board itself, it was a kit hand soldered by yours truly, however I can't see any bad traces, solder connections, etc that might be the cause.

I would like to check and see what kind of signal is actually coming out of the board on the x and y axes but my oscilloscope is currently on loan and I don't think I can get it back until friday.

Thank you for reading this.
Thank you even more if you can help me solve this problem.

Edited 1 time(s). Last edit at 05/08/2013 12:03AM by Meringue.

I've seen that on my old Gen7T design where the ground traces were long and I didn't have enough capacitance near the stepper driver 12V supply pins. I think I also found a solder bridge on one that was causing a similar problem. You could try adding some caps to the back where the isolation capacitors are and see if that helps. Sometimes too, just resoldering any pad that doesn't look absolutely pristine, shiny etc. solves it. I have made my share of hidden cold solder joints.