I have a FolgerTech FT-5 R2 that I just pulled out of the attic after about 12 months sitting there. I cleaned and dusted the printer down. I got a 25mm calibration cube going on the printer. The layers started shifting in the y-direction near the top of the print as shown in the image below. I then turned down the travel speed in Repetier Host from 150 mm/s to 40 mm/s and did a second print. That print turned out fine, with no noticeable layer shifting. I then tried to print the Windmill object that comes bundled with Windows 10. Very early on in the print, the layers shifted once again.
I checked the voltages on the stepper drivers. I wiped down the rails and checked the cabling. I even checked the distance from the nozzle to the bed. Nothing seems to be working and I'm baffled.