[Lynn Eades]

If you can push the ball down the rod against the spring, and get som oil, or clean up the rod, the spring will push the ball the other way. So I found that by compressing against the sping enough times that eventually the spring pushed the ball back, and freed up. Obviously yours are in a worse state to start with. Some are so worn, that they will never rust up.
Keep in mind that, that ball runs in a fibre cup in the bogie casting, and if the ball is not in fairly reasonable condition , it will destroy that bearing. There tend to be more suspension bits around than carriers now, so throwing stuffed bits away (when you have others) is not such a crime.
I have been lucky enough to be able to pick the best from a pile of bits.