Sorry to hear about your father. I went through that a bit back, including going through all the old books and papers.
Their original store, which is probably the one you remember, was in the 400 blk of South Main in the plaza there. They moved maybe 10 years ago to the present store which used to be one of those old fashioned hardware stores (lombard Hardware). They had anything you needed and people who actually knew things. Gotta miss that.