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I am working with support on this one. Just wondering if anyone has had similar problems and if so how you fixed them.

My whip was degenerating to the point I needed to replace it. I was getting defs after a few minutes on each print, the whip holder wasn't helping. Finally it started to blow the small fuse near the top of the Rambo. After that, when I went to home the printer, the arms would descend a few centimeters rather than homing. I did an M119 and found that none of the endstops were responding. I have reseated the endstop connectors on the Rambo (and they each appear to be solidly connected) to no avail. I have replaced the whip. I'm sure this must be something simple, but have come up empty on a solution.

BTW, a buddy suggested reflashing the firmware. Didn't make a difference.

A bit more to this mystery. I tested each endstop separately with the M119 command and each endstop does appears to be working properly. I got it wrong earlier. The controls section shows the z coordinate to be "-26843..." When I attempt to home, the arms descend a few centimeters and stop. This has got to be something simple.

I would revisit your endstop wiring and connections. When you do a home command, the arms will move up until they hit the switches, and then move down off of them. It sounds like the RamBo is getting an indication that the carriages are already at the switch, and is trying to move them off of them.

Reset your Z zero point using the front panel.

g.

Flashing the Rambo does the trick, as long as you remember to clear the eeprom first. Once I cleared the eeprom flashing the eeprom worked (using Arduino 1.6 ide)