I can move X, Y and Z in both directions to Octoprint,

I can move X, Y and Z in both directions to Octoprint, X and Y both home ok, Z will not home, but sits and whines. The Z axis is 2 steppers wired in parallel connected to threaded rods for the axis. The printer is a old Printrbot style machine. I can move Z down and hit the end stop with no problem, but using home on Octoprint causes the above issue, any ideas?
http://www.youtube.com/watch?v=VR1DByQnI1A

It might be the speed of the z-axis. Try lowering homing speed for z.

Yes, I had this problem on mine also, moving using arrows on octoprint worked (I think because there is a setup that sets the feedrate for moves on the gui) but G28 would whine and not move because it was using the config file feedrate.

After further testing I adjusted the values of home_speed for z, but that didn’t prevent the issue. The only change that kept the issue from occuring was to change the Z axis steps per mm to a lesser value. My calculated value for Z is 141.7, but I had problems with any value over about 85. Any ideas?

I am also getting this though i’m using 125 steps. i’ve tried turning speeds and feeds both up and down to no luck.

Do you have a probe on your? i know i do and i’m using Z2 for the endstop

no probe, just using z1 as the neg endstop