Parking Brake 2000 GMC Sonoma

Help,
The parking brake pedal on my 2000 Sonoma has gone from very hard to depress but still holding to all the way up, impossible to budge, no brake at all. I have read a bunch of posts with the problem being "pedal all the way to the floor" but nothing on my trouble. I have looked at the cable on the outside of the frame rail, but I don't have a clue what I'm looking for.

What may have happened is the brake pedal assembly is in a bind. look under the dash at the pedal assembly to see if there is anything stuck in it (I have seen wiring harnesses sag into the assembly).
If not, check the cable under the truck..give it a tug, if it moves then the cable is free and most likely the pedal assembly is the problem

Thank you GMMerlin
I checked for binding and found none. In checking the pedal assembly I did notice that with the brake off, the gizmo (release lever?) that the brake release cable threads through can be pulled slightly forward and then the brake will set. Once I release the brake we are back to square one until I fiddle with it again. If the gizmo is the problem, is it something that can be adjusted or does it have to be replaced?
Ineka