Stepper motors grinding

Hi all

I am currently working on assembling a RAMPS 1.4-based i3-style printer. I'm running a customized Marlin firmware on the board, and am using four DRV8825 stepper drivers (X, Y, Z1/Z2, and E0). The stepper drivers have been tuned to the correct Vref (my motors are 1.5A, so I've got just under 0.75v set for Vref).

I'm currently testing my X, Y, and E0 motors using the on-screen controls from the LCD, as well as using Pronterface. The Y-motor works flawlessly. The X and extruder motors, however, do not move at all. Upon trying to move either motor, they simply begin to vibrate and make a loud grinding noise. Attempting to move the X-carriage while doing so shows that at least the X-motor is still holding torque, as the carriage cannot be moved.

I have tried moving each motor's connector to the Y-axis stepper driver and then moving the motor, but to no avail, so I don't believe it to be an issue with the drivers. I have also checked for any obstructions, but other than the X motor having a pulley and belt attached, and the extruder motor having its gear, there is nothing around the motors that they could be jamming on.

Is there anything I can try, or do I just have a couple of shot stepper motors? For reference, these are the ones I'm using: Usongshine NEMA17

Thanks!

You can always use RAMPS_test.ino to see if hardware is working.
It doesn't care about endstops or extruder temps, so it's better to have the steppers run free. ( no belt, no filament )

When you moved the X and extruder motor to the Y-driver, did you then also use the (known to be good) Y-stepper cable? Often, the problem is in the cables...

I tried out Ramps_test.ino, with the same effect. However, when I went to plug my cables back in, I noticed that whoever sold me these cables mixed up the black and green wires on half of them, specifically the half that aren't working. So, that's much better than having broken stepper motors!

Thank you!