Good to hear. I don't think this has any connection to the craftsmanship of the amp, but I suspect it has a lot more to do with shipping. The rattles, shakes and jolts can happen to a device regardless of how much foam packing is utilized. Then again, maybe a kind note to the builder that a drop of thread-lock might be considered for future builds and that should alleviate a lot of headaches even if the package rattles a lot during shipping.
Exactly what I was thinking, I use Loctite on many screw applications where it is necessary. If the screws should loosen up again due to the heat then cooling constantly, I will apply a little Loctite. But I'm glad this was the issue with the tube sockets. Now I'm just going to wait for the new 12AX7 to arrive before making any other moves. I also didn't think this had anything to do with the craftsmanship, but more to do with shipping/customs. Thanks for the "Good to hear", I appreciate it.