You CAN repair it instead.
As I have said before - Tama lugs from the period were made from a mixture of bean mass cheese and snot, and they WILL break. So will the "new" ones you buy.
So, what you can do is this:
Drill down the remaining piece of the stud with a drill slightly smaller than the thread, and use a thread cutter to cut a little more thread - even 2 or 3 rounds will make a difference. Take a bolt or screw of the correct thread, dip it in epoxy - and turn it in, as hard as you dare, showing care not to overdo it.
After the epoxy has dried, you can cut off the piece of thread not needed - from now on, you will fasten the lug by means of nuts.
I presume, thet threads are 5 mm metric - then you will need a 4 mm drill, and a 5 mm threading tool. The cheapest Taiwan ones will do fine, as you are going to cut in an alloy of - well.....
A small tip is to put a nut on the screw, turned fully home, before glueing it in place. Before cutting the redundant piece of screw off, you now turn the nut down towards the lug - and NOW you saw off the piece. After a little filing of the end, by removing the nut gradually, turning it a little to and fro, you will make sure the thread is easy to put the mounting nuts on.
Jon