Not the easiest mod to start with.
You will need to cut the stem off cleanly, or get a donor stem from somewhere else. I would use a donor base, too. I kept various parts from several junk boards for projects like these.
The stem can be adhered with epoxy, and you will do well to make a jig out of wood in order to position it correctly. It would be almost essential that you have a proper example to build the jig around, then remove the original and set the new piece into the same setting.
I would set the naked stem in place, apply the wet epoxy, and carefully set the top exactly where you want it.
Perhaps someone else has a better idea.
