My Carbon or Graphene Tips Won Stay On The Probes

The carbon tips are made from a semi-rigid filament that can change shape according to ambient temperature and humidity. Here's a tip for a customer to keep her probe tips fitting tight.
"i used a lighter to slightly heat the black opening, then took a pliers to gently squeeze both sides toward each other. It doesn't take much heat, and just a gentle squeeze to tighten it enough to stay on."