Unless you really know what you are doing I wouldn't recommend trying to rebuild your starter. Parts are available according to the parts breakdown but to try and tell what you need will be difficult.
It may be worth your while to try and find an aftermarket starter for your motor. They are usually significantly less expensive than OEM starters. Aftermarket starters may be available from Oregon or Stens or Laser. The Honda part number for a replacement starter is as follows....31200-ZA1-003. If you take this part number and the old starter with you to a reputable small engine shop someone there will hopefully be able to cross reference the part number to an aftermarket starter. Some shops may have a selection of good used starters. You could try that too.
Hope this helps. Gil