title_body: Replace gear in Whirly-Pop with metal
upvoted_answer: Don't think you can replace only the gears, but I found lots of places selling replacement lids with heavy duty gears.  Check the link out below:
  
  WhirleyPopShop
  
  I googled 'metal gears for whirley pop' and got a ton of options.  By the way, it appears that the gearing on the lid in the link above is held together by allen wrench tap screws so you 'might' be able to scavenge the gears off the lid and put them on your own, although, if the lid itself works well, then I don't see why you would want to do that.