Here is a link to my thread about my 240D. It has some good info about the d104 element and other microphones. My D104 quit, and I accidentally fixed it and it still works. I took the element out of the head and laid it face down on the diaphragm for about a week. I guess it pushed the diaphragm back into the armature and the wax stuck back together.
https://www.worldwidedx.com/threads/robyn-t-240d-executive.233524/
https://www.worldwidedx.com/threads/robyn-t-240d-executive.233524/