It would probably be cheaper to replace the cable, check with your local auto wrecker. This used part should be very inexpensive, compared to repairing it.
I am having the same problems with a used 96 sable bought recently. No speddometer odometer trip odometer and no radio function. (also low coolant level idiot light is always on, though the expansion...
You can do it the hard way by removing the gauge cluster in the car, or you can pull the cable out of the speedometer gear in the transaxle. This should give you enough room to pull it out and oil...
The dash actually comes out as an assembly. In other words you wont be removing a lot of stuff from the dash to get it out. Remove the steering column. (4 nuts on the bottom, one steering sector...