Did you change the connections at the box, or at the motors? likely the cable inside that cable chain.
Sounds like a cable issue. I had to replace all three x, y and z cables on mine, did it over a couple months as each failed.
Can you ohm the cables?
Are you hearing a grinding sound but it does not move?
Can also try manually moving the x axis to middle, or other end, enable power to driver then see if the cable randomly makes connection and moves.
If I may give some advice, buy enough to replace all three at once... they are a very weak point of the system.
They can be found on amazon, both 4 conductor shielded cable and the connectors they use.
Another note, you may need to check your settings if you are having issues with reliability.
My machine would lose counts with small increments, it was due to the configuration being incorrect coming from the supplier.
2 ways to test if you lose counts.
1) try to jog with F=6; if you hear a grinding sound but see no movement, you are likely losing counts.
2) set up a job to run 150mm in one direction, and 1mm in the other (x,y) or (Y,X). the axis on the smaller direction will likely not move at all.
If you are not having issues, do not change anything. If you appear to start losing counts, follow this guys advice.
https://the-cnc.blogspot.co.uk/p/my-mach3-settings.html
A couple notes, he put in his own limit switches, if you do not have them, do not enable those.
Also, he has a setting to make the screen full size, I did not like it and changed mine back.