axis moves in forward direction more than backward direction

hello I am building a 3d printer called "e-waste", it is based on steppers gotten from old floppy and cd-rom.Its electronics are based on ramps 1.4 and its firmware is based on marlin 1.02 firmware. I am trying to move manually the steppers from repetier or pronterface. I could move them successfully, but I noticed that when I move an axis from the software to move 10 and then -10 (for example) I found that motor does not return to same place. I notice that motors moves in a direction more than the opposite direction. I tried to play with pots of current limiter in stepper driver without success. any ideas about the possible cause?

You are maybe trying to move them too fast. Steppers often work in one direction better than the other. One of the things you pay for in top notch stepper motors is the knowledge that they will work almost the same in both directions. If your steppers are from printers they may well be designed to move in one direction only anyway.

Just try slowing it right down to see if it behaves properly.