[8] By 1976, Sanborn was offering the traditional Latin Mass for Catholics on Long Island, New York, United States, together with Clarence Kelly.

[4] In 1977, Sanborn was teaching at a seminary of the SSPX which was then called Saint Joseph's House of Studies, in Armada, Michigan, United States.

[16] In 1995, Sanborn founded the sedevacantist Most Holy Trinity Seminary in Spring Lake, Florida, United States.

[20] Sanborn currently serves as the Superior General of the Roman Catholic Institute and as the rector of the Most Holy Trinity Seminary which was relocated from Brooksville, Florida to Reading, Pennsylvania in Fall 2022.

[3] He frequently visits Mass centers in the United States and occasionally travels to Europe, meeting with sedevacantist clergy and laity.