Rain,
Been thinking along that line too. I have no idea how it's held together. No set screws on the numbered dial, just a snap ring in a grove that abuts a pin of some sort. And I have no idea how it is secured to the machine. I looked at it when I had the clam shell off but couldn't see any sort of set screw.
I'm going to finish up the bobbin end, make a gauge to make sure the substitute needle is seated out correctly then check the timing.
After that I'll pull the shell off and see what I can do with the top tension.
Joe