The bushing in the drive hub is the weak link it will definitely wear out first. The only way the crank could wear is if the bushing disintegrates and you were left with steel on steel. Make sure that you spray between the crank and bushing every time you come off the track that will help with the wear. I use either WD40 or Tri Flo. If you have a lot of side wobble it could be a combination of a worn bushing and or to much clearance between the drum and crank spacer. Below I have put a link to the Horstman Spec and rebuild instructions. I hope this helps.