I drilled holes through the sides of the nub at the back of the claws and ran upholstery thread through them, looping it through the plastic canvas structure on the inside of the paws. Gooped a bunch of E6000 into the hole that the claw fit into, then pulled it tight with the thread. Here's hoping it holds well! Those claws are solid and surprisingly heavy. I may clack on the floor when I walk with them. :)

The lump on the side of the right paw is the part that loops around the heel of the shoe bunched up.

Hmm, the grey hilights don't look symmetrical. Have to re-examine that from head on.