Quote Originally Posted by skimask View Post
For S & G 's, maybe throw a couple of thicknesses of aluminum foil between the board and the motors (taped up or coated somehow of course so it doesn't short out) and ground the foil...see what happens... Might help with the EMI if there is any.

And if it doesn't work...at least it'll keep little green aliens from invading your Treadbot with their evil mind control devices!
The aluminum foil will work for aliens but if the problem is a magnetic one you will need something with a high magnetic permeability. Hold a compass near the motors when they are running and see what happens. Use one that you will not care if it gets reverse polarized.

If this is the problem, all you should need is a thin piece of cheap steel (roof flashing) that is a little larger than the board being that the motors are underneath it.