I made an appointment for the Flagstaff dealer to check it out next week. I ordered the seal kit, so it will be on hand. Polaris doesn't sell individual seals, only a kit with all the seals for the differential. Hopefully it will be an easy fix.
AA: actually, I guess I lied a bit about the mileage. I was guessing when I made the original post. I just checked and it is at 17,399. My friend and riding partner has the same machine, and just turned over 20,000. BTW, I see that you are in Dublin, OH. I lived in north Columbus all my life, until I retired in 2005.
Tom, camping in the Ponderosa Pines in eastern AZ