Screen Calibration on Android Tablet

[zorgan]

I have replaced a digitizer on a Chimp Tab 9" A19 tablet, however anytime I put my finger on the screen it's aiming about 1cm higher on the screen than where I put my finger (pixel offset issue), does anyone know if there are any apk's out there I can install which will let me scale the screen properly as the Y axis is off a few digits and it's really difficult to do anything on it.