Solved Y-Axis only moving in one direction

I've been futzing with this thing for about a week now trying to get the Y axis moving smoothly. I bought the igus bearings but if you tighten it down too much it catches. I gave up and I have standard LM8UU bearings coming. During the process I was moving the Y axis back and forth to test smoothness.

Now the Y-Axis only moves in one direction when I try
Here's what I've tried:
1 - reverse the cable and the Y axis stepper moves in the opposite direction. So stepper appears to be fine.
2 - Swapped the motor driver from another axis (x-axis). still only moves in one direction

What else could it be?

 

Thanks for the quick response, looks like the switch is indeed come undone. just need to find the wiring diagram now to put it back and test it.

 

thanks. I think I got it going but now the Z-axis doesn't work when I auto home it. I didn't touch the endstop switches there. It just wants to keep moving downwards.

I don't know which printer. it has a white Ramps board.

EDIT: If I manually move the Z-axis all the way down works. but when I hit print or autohome it wants to keep moving.

 

I checked that both are seated properly.
here I am manually moving it up and down even against the bed:

edit: If I push the X axis up to trigger the switches it will stop trying to go down. It just seems to stall either when it wants to print or autohome. everything else works.

if the driver adjustment is off would that affect it? it looks like the little metal philips screw plate was bent up, maybe it got shifted?

 

Yup. That was it. The trim pot got moved some how. just cranked it a little bit to match the others. Persistence paid off, back to printing! This was prevented just in time i think: