[Mgs] Disassembly of throttle shaft from HS-4

[Simon Matthews]

I have take the throttle shafts off my daughter's '71 MGB-GT with the
intent of replacing the throttle shafts.

I have got the shafts out, but cannot figure out how to disassemble
them. The new shafts have a thread at the end where the levers are
fitted, but the old shafts don't want to unscrew.

See picture of the old shaft here:
https://goo.gl/photos/8UaWuTs8aefQiRf68

Can anyone tell me how to get these things apart?

Simon