How do I remove the broken end of the tach drive recessed into the end of the camshaft on my massey ferguson 65 diesel

Hi Bill:
Here's a trick you might try. It should work if the broken part is not physically attached and if it is magnetic.
Find a short piece of plastic tube, even a drinking straw will do, that will slide into the hole.
Find a common nail that will just slide into the tube. Grind the pointed end off the nail so it is flat.
Slide the plastic tube over the nail also that it bumps into the head, then cut the tube off flush with the flat end.
Slide the tube with the nail in it into the hole in the end of the crankshaft.
Take your handy super magnet and touch it to the head of the nail.
If you are lucky, if you gently pull the nail/tube out with the magnet attached, the broken but will come out.
Hope this helps.