Hi: Please note that most of Madison is not in EAST Somerset County, which stops east of the Kennebec River. A small part of Madison IS east, that is East Madison. I did not find that town included in the Register. Unfortunately, the records of Madison are no longer available. There was a fire; but then the records reappeared, hidden away in a corner of the Madison Library, with the edges of the pages charred. Later they disappeared, and it is suspected that they are in private hands. I did look up the name Russell in the Skowhegan history by Louise H. Coburn, and there were 4 men with Revolutionary service. All were born in Lexington, Mass., and had later moved to Groton, thence to Maine in 1793. It is possible you could do an LDS search for deeds in the name of Andrew Russell as grantee/grantor at the Somerset County Registry of Deeds in Skowhegan. You might find a deed or probate with useful witnesses, names or relationships. The town of Madison would have been Kennebec Co. between 1799 and 1808 (shiretown Augusta, ME), then Somerset Co. from 1809 to the present (Skowhegan).
Good luck. Kathleen