@immatthewj, I understand your rationale on returning the unit that is not working the way it should. I feel bad because MD had already replaced my unit once. They actually were going to repair my first unit, but I asked for a replacement, and they were happy to accommodate me on that. Since this is the 2nd unit, and a custom order, they are less flexible on that. But it's nice that they offered me the option of returning for a refund on a custom order. You are making me change my mind now 😀
This thing with the tubes not seated properly can cause failure seems bizarre to me. If this is indeed the root cause, I would argue that it is a design flaw. As you mentioned in your previous post, the fact the tube sockets are sunken in below the surface can be problematic. You can't see whether your tube is properly inserted. You can only go by feel. Being a newbie with tubes, I tried to be extra careful of not using too much force, worrying that I might break the tube. I think Cary should have better documentation on how to insert the tubes.
Let's see how it goes. Hopefully it's a minor issue.