Man its been a long time since ive done one. Not too bad of a job though, if I remember correctly. Id just make sure that you replace the plastic dowels that hold the gears in place, youll see what im talking about when you take the metal gear off to transfer it to the new motor, you can get the dowels in a kit at most parts stores.
Like I said, not real bad, take your time and pay attention to what your doing.