When your Slinky gets a knot, it may not be able to walk down stairs or perform other fun tricks. Untangling knots from your Slinky requires a lot of time and patience. Since the untangling process tends to stretch out a Slinky's coils, your toy may never be the same after you fix it, but if the knot is near the end of the coil you may have more success.
Use wire cutters to cut off knots near the end of your Slinky's coil. This way, you get rid of the knot without stretching your coils, which can damage the toy. For knots more toward the centre, you'll need to untangle them by hand.
Pinch the sections of your Slinky coil a little to the right and to the left of the knot and push in to loosen the knot.
Slowly work the shorter side of the Slinky coil through the loosened knot while holding the other side to keep the knot loose. Work carefully to avoid stretching and warping the coils.
Continue working the Slinky coil through the loosened knot until you reach the end of the coil.
Repeat this process for any other knots in your Slinky.
Be especially careful when untangling plastic Slinky coils. They snap easily.