Partially Solved Calibration Cube

I've been printing for about 8 months on an R1+ and gotten decent quality out of it just winging it. Recently I discovered all the online resources and forums and guides and have been trying to do what I can to improve my print quality, but I've been having trouble with my X axis.




I'm printing PLA and have tried a multitude of different temps, speeds, retract settings (2.5 / 50mm/s for this print) and I still have trouble with only the middle portion of that X. the Y and Z come out perfect. What mechanically could be causing this issue on just the X axis at that Z height ? the Y at that height is perfect...

 

For the record this is a repeat problem, I have been having the same issue at same spot with different settings which is why I am thinking it's something mechanical possibly.

 

Yeah using CuraEngine on Repetier Host.. dont have the money for Simply3d

 

same results using slic3r and matterslicer, but a uh friend of mine let me use his copy of s3d and it cleared up. so it's some setting I'm missing between default s3d settings and every other slicer out there. idk? i'll compare settings closer tomorrow, i appreciate someone responding at all though