I have a Printrbot simple metal 1403 with x axis extension (installed 6 months ago) and heated bed (1 week ago). I am using a printrboard rev F6, which was also installed a week ago with a new power supply to handle the heated bed's current requirements. After installing, I flashed the 8/10/2016 firmware update. I forgot the M502 command initially. This resulted in the y-axis running just a few mm at a time in the wrong direction when the y-home button was pressed. Everything else worked fine.Once I figure out my mistake, I re-flashed the firmware, and sent the M502 command. Everything worked, and I ran a 6 hour print with no incident.
The following day, I went to print and the same behavior was back. Y axis moves a few mm in the wrong direction when homed. I tried the M502 reset to no effect. The behavior continued. I flashed the firmware again and the problem was again resolved.
Today, I have the same problem. What the heck? Anyone have any experience with similar symptoms? Any ideas where to start troubleshooting this kind of problem? Any help would be appreciated