Remove the garment from the press and check that the new snap clicks into the opposing side.

A properly secured snap will flatten the cap post into the sock/stud piece. Depending on the type of snap dies used, this will produce one of two outcomes:

Three concentric circles visible at the center of the snap (reference image #2)

A mushroom dome shape at the center of the snap (reference image #3)

If the snap spins in place, the snap isn't secure. Repeat the previous step.

If you're replacing both sides of the snap, repeat these steps on the other side, ensuring all the proper dies and pieces are used.