Retrieving Stuck Nuts
Have you seen the price of nuts these days? Leaving a jammed wire not only leaves a hole in your pocket but robs the next leader of a truly true onsight!
If it's a toss up between following a pitch "pitch clean" or getting the stuck gear out remember you can always lower or ab back down after, it's no big deal.
Carefully use the nut key on the metal of the nut rather than damaging or fraying the wire.
Create a "zinger". Chain link a load of krabs (maybe 10) into the wire and give the other end a sharp tug. This creates a massive impact force on the nut - if this doesn't move it nothing will!
If the nut has locked into an expanding flake/crack place a cam in beside it and put body weight on it (safely) this often opens out the Crack sufficiently to loosen the nut!