Balance and shoe pivot assistance

Hello, I'm hoping you folks can assist. I need to replace the shoe pivots (not sure if this is the correct name), and ideally I would replace just the bottom pieces of the balances. The balances themselves are ok, but the plastic pieces at the bottom that attach to the shoe are breaking off. Pictures are attached, but I don't have one of a complete shoe bottom. There should be a small mushroom cap or button on the shaft if it were complete. 
 
Thanks!