Homebuilt I3 that has been running fine with lots of printing for the past two years. Last week it started printing everything a little over half size. I figured the program got corrupted so I resent and retested. Same thing. Put a new Mega and Ramps board plus all new drivers. Took time to carefully calibrate the current, retested and same thing. Tried Cura 2.6.2, Slicr 1.33.8 and repetier 1.6.2 with several patterns included 25mm test cube. All prints are about 60% in size in X, Y and Z. I checked the steps per unit and they are dead on.

Any ideas what this could be?