Thanks for your suggestions, however I don't think that buildup or lack
of lubrication on the steel rod upon which the print heads travel is the
culprit. I carefully inspected mine and found it to be free of anything
that might stop the print heads from traveling back and forth. It had a
little bit of ink on it. I cleaned and lubed the rod with a small amount
of teflon lube (Tri-Flow) but shortly thereafter the heads stopped in
the middle of the rod again once it had finished printing. I turn off
the printer, push the print head all the way to the right near it's park
position and turn the printer back on. Usually it's good for another few
prints before it parks itself in the wrong position again.

Still seeking a solution.