I was mistakenly under the impression CD-R's were a permanent format back in the day. Turns out the cheap, what was considered "low quality" cassettes back in the day, are more reliable today than CD-R's. The audio cassettes I transferred this evening are 40 years old. The failed CD-R's are 20 years and newer.
The new digitized backups I'm making of the old recordings my friends and I made back in the 80's are going to be backed up twice, on two external hard drives, to make for easier duplication. Saving in both WAV and MP3 formats.
I'm transferring the earliest "original series" we recorded first, from 1981, and will work my way up. I've finished episode 8 of "Life of Elvis" out of 14. The eighth one has the worst sound quality, the Xmas special for that year, but I did the best I could with cleaning it up on Sound Forge. Randy recorded that at his house on a cheap cassette on his own equipment, a portable monophonic cassette recorder with a "Dorchester" brand turntable.