I appreciate all the advise as well.
I have 4 cheap/fragile looking normal bias tapes from around 1984 - 1988, of my Grandfather (passed away in Sept 1991) playing his keyboards, and recording me, my sister and cousins singing, playing records and games.
My plan is to use my DR-1 to transfer these but I'm pretty concerned as I don't want to risk ruining the tape. Of course they're extremely valuable to the family, and I've waited till I felt comfortable enough with attempting to preserve this audio.