Caspari pegs work by having a bushing glued into the peg box on the "head" side of the peg. The bushing is made of what I believe is transformer coil material. The Caspari peg then squeezes against the sides of the bushing. The screw at the end adjusts the pressure against the bushing.

How to fix problems with Caspari Pegs or pegs that work in a similar way.

• The Peg is slipping or is too tight. Tighten up the screw by turning clockwise. Usually you can find a coin that fits into the slot.
• If it still slips, check to see if the bushing is still glued in. If the bushing slips, simply glue the bushing back in.
• If after making the screw as tight as possible it still slips, the bushing is too worn out, it's too narrow. You can make a bushing shim out of a fiber material with a hole in the center and the size diameter would be the same size as the bushing. This gives the mechanism enough space to squeeze onto the bushing.
• You could try the suggestion that Jacob gave in the comment section below.

The bushings can also be removed. Remove the Caspari pegs, then check the bushings and see if you are lucky enough that you can twist out a lightly glued bushing. If not they need to be drilled out. Carefully drill a slightly larger hole. Then keep stepping up the drill until it is just barely under the size of the busing's diameter. Then with just a little bit of bushing left, you can chip out the remainder. It's not really a good idea to ream the bushing out to a normal peg shape because, the material is quite hard and it will wreck your reamer, plus there is usually a little bit of bushing material protruding into the peg box. Leaving that material will chew up the strings.

Once the bushing are out, you can ream the holes to the normal peg shape and then fit oversize pages. Alternately you could use a spiral bushing on the large hole and then ream to a normal peg shape, then you can use normal size pegs.

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