echo:endstops hit

Hi,
Building a machine here (own design) and have a problem. Using the Marlin firmware and Ramps 1.4. Trying to move the z axis, but it moves down ok, while not moving up successfully. It throws a "echo:endstops hit" message and stops moving after a tiny jolt. My endstops are not hit, M119 shows them as open. My only guess is that my fairly heavy bed might be causing this, straining the Nema 17 Z axis motors. Could that exception be caused by this somehow? I tried 2 PSUs, so I doubt that's the issue. I was hoping for some guidance before I resign to get Nema 23's for the Z axis, and possibly a bigger PSU.
Thanks.

Endstops are normally triggered when the switch is open,

I would guess you simply have a bad connector somewhere in the endstop/cables/ramps/mega and its momentarily going open circuit.

This could also be electrical noise if your motor wires are two close to endstop wires

I doubt it's electrical noise, they're very far apart.

Not sure HOW it happened, but it seems you're right in that something is tripping the endstop. I removed it completely and now it works. Will have to work on that one.