Hi Adam,
Note on the Piano 27 rebuild that there are four screws for the mouthpiece receiver. Two are machine threads and two are wood-screw type threads. The machine threaded screws go in the top. You can see a metal pad inside the mouthpiece receiver into which the machine screws are screwed. I did not pay attention to this when I took mine apart and got them mixed up, ruining the machine thread in the mouthpiece receiver.
Lowboy