Thank you so much! The idea of tapping the parts was one of the first, that crossed my mind, but I put it on hold due to the fact, that I wasn't sure how common the screw threads were back in early 16th century.
I really wish people at Met would let me handle theirs.
I have seen the picture in Fernando's post, one appears to have the spring on top, that latches the bar in, the spring idea is also on the table at this time.