Stuck brake cable?
 

In the process of removing some old Dia-compe non-aero levers, I've found that the cable end is slightly smashed into the lever body, in the swiveling holder. I tried yanking the ball tip out with some pliers, then found that the little end ball was actually cracked, and the top of it came off. Now it's looking really jammed. Any suggestions on how to remove this, and why it happened in the first place? Was the cable too tight when it was attached to the actual brake?

Arg, frustrating.