Hello Bill,
Thank you for your valuable feedback. You are correct the replacment moter does not come with that replacment o-ring. We will asure your feedback gets to the proper person(s) in our organization. Please feel free to contact our product support team if you are in need of any additional parts. They can be reached at 1-800-835-0113 Mon. - Fri., 8am - 5pm.
Thank you,
Great Plains Industries