There's nearly always a way to repair most things Larry. I assume these are MG's mounted by a single stem to the vehicle??? In this case, all it usually needs is to drill out where the stem meets the MG - and where it was once mounted before on the vehicle - and substitute the soft metal stem - for a piece cut from more solid metal - I usually use a piece cut from a paper-clip. Then, just super-glue it back in place - wait until set - and re-paint the stem carefully in a suitable colour. It will be stronger in steel, than it was before.
Alternatively - there are professional repairers who could do it for you, ( there are some good guys on this Forum who advertise repairs).
I would also post your message in the CS part of the Forum - for more advice from collectors of this marque, on a possible replacement part. jb