Is the cable whole and stuck? Another words is the end of the cable (that presumibly is stuck) still attached to the rest of the wire? If so then the usual solution is to work with the cable wire as it leaves the lever at the same time as working with the lever paddles and try to find the magical combo of pushing and levering that allows the cable end to unwedge.

If the cable end is broken off the rest of the inner wire then you move to trying to hook it/push it out with dental like tools. usually this situation is worse since there's no inner cable wire to help prod the cable end with. This is why you should replace the inner cable wire before it breaks!

Taking the shifter pod apart is not for the faint of heart. It's not considered to be servicable this way by Shimano. You do read of some who have done so and been able to reassemble it and have all work well. But as a shop we would never suggest or offer to do this. In the end if the cable won't come out and restore the lever's full function it's replacement time.

If the cable end was not kept well seated into the rotating spool, then the lever was clicked a few points the spool could rotate and the cable end would stay put. then if the cable was to be pulled the cable end could wedge itself past the spool's seat and between the spool and the body of the unit. Andy.