I broke the wire off in mine years ago. (before I had a torch.) I forced some kind of stiff wire in the slot with a hammer and vice grips, if I recall correctly and it pushed the old wire out ahead of it.
My impeller had a pretty bad shoulder for the seal to go against. Back then, my cousin the auto mechanic pressed a 5/8 shaft in the impeller and chucked it in his valve grinder and ground the shoulder back smooth and true. His grinder was military surplus, he bought it from the supply depot when he was stationed in France in the 50s, so it could chuck a valve with a 5/8" stem. He's gone now, and I no longer have access to his tools.