I'm not qualified to answer your question, so I will tell you a story. I once got a check from a well-known publisher in the amount of 38,000 dollars, with a letter saying, Here are royalties for such and such a book for the past 9 years. Sorry these are late but, um, see, we lost your address. It so happened I had read in the business section of a news magazine that this particular publisher was selling off some of its divisions, so naturally outside accountants had been called in. About this time I also heard that some other authors also got big and unexpected checks.
Did you know that CLOUD HORSE by Jill Pinkwater is now available in a Kindle edition? Very good book. I think everyone should order it. You can get Kindle books on your PC, did you know that?