It sounds like you are correct in your diagnosis.
For the parts microfiche, you can go to Service Honda or Bike Bandit's websites, and they have them on there. To access the seal, you have to pull the right side cover, the clutch, primary gear etc off. Once in there, you can pop it out, and replace it, then reassemble. A manual helps for the torque values. It isn't too bad to doo, but you normally need an impact to pop the primary drive gear off the crank. A seal remover and seal driver make life easier as well, but with caution, it can be done with improvised tools in their place.