Having increased frequency of intermittent shifting in x-axis.
What hasn't helped so far:
Tightened all the set screws to the pulleys including the ones attaching gear to stepper motors
Checked tensions on all belts including short belts.
Marked the pulleys and rod locations with ink, have not identified any slippage at marks after multiple shifts.
Removed a piece of the LED lighting with adhesive failure causing it to drop into the pulleys.
Slowed down the prints, reduced acceleration to 1500.
Here is a video of such a slip occurring- http://vimeo.com/114431802 at the 10 second mark, a sound is heard but I can't locate where the issue is.
Head does not seem to be snagging on anything raised in the piece.
Occurs with a variety of print settings- this particular occurrence one was PLA 200C, 0.1 mm layers, 35mm/sec with 70mm/sec infill.