Sorry my original reply I thought you were talking about a flash stuck on the shoe... I have had that happen.
No clue on this one. You stripped the plastic wheel, from the metal shaft. Just leave it on!
Dan at Berry's camera has fixed many Nikon maladies (like flashes stuck on bodies because the pin wont release). 765-742-0297 (Indiana)... likely NPS will fix for at least $200.