I have a lot of CdRs in my collection and unfortunately I have discovered that many of them are now unplayable: Vir Unis "Lumen"; a couple Saul Stokes (those in the wooden boxes); James Johnson "Lost at Dunn's Lake", "Unity", "Surrender", "Minimum", "Journeys"; a bunch of Dark Duck titles; a mountain of Mathias Grassow titles. My discs are stocked in a safe place - no humidity at all - some of them have the paper label, some don't. I've tried to get the replacement discs from Saul, but he replied that the masters are gone lost.
I've always replaced all the defective Umbra and Penumbra discs, so I'd like to get replacement discs when I need them, but in many cases this seems impossible.