The cue bar that lifts the armtube may not be parallel to the record and might cause the arm to move outward.
The cue bar might be rotating slightly when the piston raises it. They have anti-rotation locks, but can move a bit back and forth.
The cue bar might be loose.
The internal wiring, going through the pivot, might be dragging a bit and pulling the arm outward.
Antiskate may be high as previously mentioned.
I've seen all of the the above.