Siebter
Less soul, more mind
that inner glass sleeve that you are referring to, that had cracked for people, is not the stock setup. It comes with an aluminum tube, I remember that glass sleeve was offered on the website later...
Not quite; there was a glass replacement for the aluminum tube, but that didn't work for very long. If you remove the aluminum tube, you will find a glass liner covering the wood under it (and the replacement for that is still available).
There is too much clearance at the base/coil area and the stem walks sideways a bit when fully engaged.
Perfectly normal and not an issue, the stem has a bit of sideway play and should still get a good seal. What's the issue anyway beside the vibration, are you able to have a session somehow? Who sold it to you?