A few weeks ago a shift between layers in the y-direction (from the front to the back of the printer) of my Makerbot Replicator 2 appeared.
All prints have some small shifts between layers, but if the extruder has to move large distances (e.g. when I print the same object near the front and near the back of the print bed), they can reach up to 2 cm or so. In those cases the extruder seem to move the wrong distance towards the back, resulting in a shifted layer, and then moves about the same distance towards the front. Therefore objects at the front of the bed often are shifted less than at the back. Here's an example of some small shifts in the 3D benchy (printed near the front of the bed). They are particularly obvious in the hull and in the supports of the cabin:
I've tightened the pulleys, lubricated the rods, restored the device to factory settings and made sure the connectors are plugged in properly, but the problems persist. I also have the impression that the locations of the shifted layers are quite reproducible.
From what I understand problems such as these along the x-axis, are generally caused by broken cables, which are pressed upon as the extruder moves. However, the pulley for the y-axis doesn't move, so it seems unlikely that the cable is the cause.
Any help is very much appreciated!