My AVX is the same - it doesn't spin freely and (seemingly) endlessly around. There is a physical stop at either extreme.
What I'd suggest trying is (obviously without any scope on board) disengaging the clutch and spin it around til you hit the stop. Note where it is. Then spin it around until it hits the other stop. Note the position. Then Spin it to the mid point. Engage the clutch. Then use the motors to centre. Power off. You should then not hit the stops so long as the clutch remains engaged.
I'm just speculating, but I don't think there's much extension past the meridian in either axis, hence the stops. I've never noticed this behaviour with my EQ6 though, so they must be engineered differently.
Edit: my bad, I was speculating as to whether they were the same, clearly not
