Removing the magnetic media is one of the best ways of cleaning the disk surface, but I'd be wary of using a circular pattern. When you clean in circles, you potentially drag abrasive dirt in circles along with the recorded data track, potentially wiping out the entire track by scratching it away. I'd suggest cleaning in short strokes from the hub, outward, like they recommend for CDs. That way if you drag a piece of dirt along the surface, you would drag it across the tracks instead of along them. A small scratch perpendicular to the track would have a far less degrading effect on the recorded data. On Fri, Aug 14, 2020 at 9:04 PM David K via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

I recently bought a 5 1/4 version of Witness from infocom. I bought it for the contents as the listing said the disk was bad. Visually looking at the disk it looked dirty.

I used a sharp hobby knife to open the disk "envelope" at the top edge (the edge you hold when you put the disk in the drive). This allowed me to totally remove the magnetic disc itself - being careful not to touch the magnetic parts.

I used 90% rubbing alcohol and a cotton ball. I cleaned the bottom side of this disk because that was the side actually read by the head. I used moderate pressure and cleaned the disc in a circular pattern from outside to inside. I could see some dirt on the cotton ball. I let it dry completely and then put it back in the "envelope" and tried it in the drive. Initially it did not work but after repeating the same process two more times the disk has been working.

I have used this same process with other "dirty" disks and been successful maybe 30% of the time.

David K