The more I think about this the less I can see where things are going wrong. The DROs show the axis in the correct positions, presuming the toolpath does too? If I recall correctly I am sure Art said Mach monitors directly at the port and updates the DROs from pulses it puts out, so that would kind of make it seem Mach is putting out the correct pulses. Hopefully Terry will chime in and tell us what he saw but I suspect he actually saw the DROs and the Toolpath showing the axis going wild.
So whats left then, hardware issue I suppose but not really sure how that could be the issue unless a Dir change is not being seen by the drives or something like that.
Hood