The wonderful thing about wills in Fulton Co. OH is that some survived the fire in 1865. The wills can be found in two different places.
The first place to look for wills in the county is at the county court house in Wauseon. Remember the staff is limited and be patient with the courthouse folks when requesting information. Dates for the wills run from 1859-present.
The second place to look for wills is at the archives in Bowling Green, OH. Here they have all the wills that run from 1859-1970. I believe these are all on microfilm.
Remember when looking at a will to make copies. It is very important to connect all the names in the will. Many times this will be your first clue of a daughters married name. Executors should also be traced, because they tend to be relatives or in-laws. Be sure to check for both spouses and be sure to check for more than one filing of a will. Inventories of estates are also important documents to locate, because they provide clues to the existence of family bibles
Good luck in your search.