Do you still have the vinyl albums or only cassettes? There are some free software programs out there that let you hook a record player or cassette player to your computer then you can edit the scratchy stuff out and convert to cds or digital files.
It's not real hard but you need to be comfortable with the computer and it does take some time to learn it and get the procedure down. I did a "campaign" piece for a board I ran for a couple years ago - took a cassette recording and made it onto a cd. Let me know and I can look up what I used.