Stuck rappel rope? Try the “rubber band” trick
You start to pull the rap rope, but can’t get it moving. Try this.
You and your partner grab opposite ends of the ropes and pull, hard. One of you keeps the “pull” pressure on, while the other suddenly releases their end. The “rubber band” effect of one end of your dynamic rope “springing” upwards often will get a stubborn rope moving.
You can do this with a Grigri or similar belay device; this might let you apply a bit more force to the rope instead of just pulling with your hands.