It could be a lot of things, unfortunately. For example, the assembly inside could be slightly bent if the gantry was moved by hand, one of the bearings could be worn, etc. We had this within the first year of having the 8000, a long time back, and they replaced the entire gantry under warrantee. It never happened again, and ours has since been sold and found a new home.
If no one chimes in with additional suggestions, I think it might make sense to give the experts at Wizard a ring for this problem. They may even want to see/hear a video of the symptom, to help diagnose it.
My 8000 does that too. It happens only in the first few inches of travel from the "home" position.
I talked with Wizard CS about it years ago and they didn't seem to think it was an issue as long as the machine still cut correctly.
If memory serves it could be the chains in the drive mechanism making contact with the plastic cowling that covers the left hand side and bottom of the head. It's fairly thin and can get bumped out of position. Try removing and reinstalling that cowling. It's only the one screw on the face that holds it in place.
If the machine isn't cutting properly, call Wizard CS.