Is this an example of what backlash can do?

[blackburn mark]

HOLY S**T!!!!:rofl:
dont you just hate it when that happens!
looks like the mountain off close encouters :)

looks like a shitload of lost stepps to me
id zero your tool and DRO's in mach on a point rapid XYandZ back and forth for a spell and get mach to go back to zero

im gussing it will stop miles away from your refrence point, if it dose you need to back off your rapid speed in motor tuning

going off what you are saying, if its reading +70 on the X axis and is more like +75 then your losing stepps when the X axis is moving in the minus direction, it maybe during a rapid or during a cut (cant tell without seeing the tool path)
what ever it is you need to lower friction on your X axis or stop driving your X stepper so hard