One woodcarver in the Northwest fixes the spirals as follows:

• I drill a 1/4" hole approximately the length of the shank
• insert a 1/4" piece of a finish nail in the hole of the spiral
• pour epoxy into the hole (about 3/4 full), and then
• insert the spiral with the bit of wire (nail) extending out both sides,
• pushing hard until it is fully in - making sure the spiral is straight.

He further notes, "I tried drilling a hole through the back of the piece, but sometimes I didn't hit the hole of the spiral, so I discontinued that way real quick."

NOTE:
Photo is approximate. Dimensions may appear different, with different monitors and different resolution settings.