In 1985, Amsterdam Oil Heat Corp. was sold to J. H. Buhrmaster Company, and Isburgh remained with the company and was manager of their Amsterdam office until 1990. After retiring for a brief period, he returned to work as an executive assistant in Buhrmaster’s main office until his final retirement in April 1999.
Survivors include his wife, Mary Frances Kinsman; two sons, Robert and Andrew; a half-sister, Carolyn McCoy; and three grandchildren.