Again, I haven't seen one, but strongly suspect they're using the same oven (why reinvent it again after Air?). It's not realistic to expect it to be exactly centered, there are too many bits that effect its exact placement (which is why the hole in the top is bigger and the part you're worried about is compliant.....this is a glass part in a tight fit. "Something has to give" or you get broken glass. Or stems that fall out.
That part ('brace ring') FLOATS, it is intended to move to match alignments.
I believe what you see is quite normal. And I trust Arizer when they tell you the same thing. No reason I see to return it, I'd start enjoying it. In the end it's a tool, only really useful if it does a needed job.
OF
Yes, it seems the same oven.
I understand what you say, the glass must be tight fit.
But I ask to me why the "brace ring" should be floating , if it's screwed with the white body ?
Maybe you meant that the upper piece when you say "float, it is intended to move to match alignments" ?
But then, if I had to remove the upper piece (the only piece that does not seem strong fixed ) , seeing how it is made the body and the brace ring, I should see all centered, therefore.
That is, I believe that, as you say, must be some tolerance and something must be "soft" and/or float for hold tight the glass, but I wonder why they can not keep everything rather centered.
Anyway I trust Arizer, and yes, I agree with you that it's useful if it does a needed job , but also that it did it for how it was designed and in the best way :-)
Only, if it were possible, I would be happy if I could see more device for comparison.