Removing Jammed Equipment
If nuts or cams get jammed on single pitch crags the easiest solution is often to finish the climb then arrange a suitable belay and abseil down to the piece. This should be done with a prussic knot back up on the abseil rope to enable you to get both hands on the stuck gear. As the prussic knot back-up is not infallible a further safety precaution should be taken. This could be to wrap several turns of the rope around your leg or have your partner at the bottom of the crag holding the ropes as well to lock them off. You are then in a position to give all your attention to freeing the jammed equipment. But what about stuck gear on multi-pitch routes? It may be impossible or at least very difficult to retrieve stuck gear by abseil on large multi-pitch crags. In these situations it is more important for the second to be able to retrieve any gear placed by the leader as they follow the pitch.
The first thing is to get both hands free to attack the stuck gear. At its simplest this could just involve communicating with the belayer above to lock the belay device off while you hang on the rope to retrieve the gear. However this only really works on straight-up routes on vertical or slabby ground.
Better than that is to try and place another piece of protection above the jammed piece and clip directly in to it with a sling or quickdrawer. Make sure your belayer is locking off the plate in case the piece fails while you are weighting it. This method can still be beneficial even on straight up routes if you are a long way below the belayer.
With a lot of rope out there will be plenty of rope stretch and it will be difficult for the belayer to hold you at the exact spot you require. If you do not place another piece to clip into, and if the route is overhanging or diagonal in nature you will end up having to use one hand to hold you in position and so only have one hand free to remove the equipment.
Not So Stuck
Having positioned yourself right next to the stuck piece you can now free both hands to get at the gear. It is then amazing just how often the nut that seemed completely jammed while you were clinging on and getting totally pumped will, with a bit of wiggling of the wire and tapping with a nut tool, slide easily out.
If that does not work you may need to get more physical. Use your largest hex or nut to hammer the end of the nut key onto the stuck nut. If there is a nearby ledge with loose rock on use a small rock to hammer with.
Be careful not to drop any rocks as you could injure parties below.
Freeing Stuck Cams
And what about those expensive cams? Cams often get left behind if they are over-cammed or where they have simply walked deep into a crack and are hard to reach. The trick here is to be able to be able to pull out on both sides of the trigger bar at the same time as pushing the stem in. Having secured yourself to a new piece just above the cam take 2 nuts and slide the nuts down the wire a short distance. Place the loops of wire over the trigger bar - one on each side. Then clip a karabiner to the loops at the other end of the wires and clip that to the belay loop on your harness. You may need to use a sling or extender to get the correct length.
By pressing your feet against the rock you can now pull outwards on the trigger bar. If you do this at the same time as pushing in on the stem with your fingers you should be able to release the cam. If you can't reach the stem with your fingers try using your nut tool to extend your reach.
If the placement is very over-cammed it may be necessary to try and move each cam in turn. Do exactly as before but this time as you pull out on the trigger and push on the stem you need to get the nut tool behind one cam and try to pull it out a little. By doing each of the 4 cams in rotation it should be possible to "Walk" the cam slowly out of the crack.
Cams with a Ring Pull System
If you have cams with a ring pull rather than a trigger bar system you will not be able to put wires over the trigger. Instead hook the ring with your nut tool and clip the other end to your belay loop as before. A little patience is required to free jammed equipment but that is more preferable than having to buy replacement kit.