[cctalk] Reading Old Floppies

When reading old floppies, how often is it advisable to clean the drive? I managed the first 3.5” floppies no problem, I’m using a USB Floppy Drive hooked up to my Mac Laptop, I was able to image them using “Disk Utility”. The next two floppies have had errors. Though I think I was able to successfully copy all the files off the one. Also, what is floppy drive cleaning fluid made of, and how well does it age? I know I’ve got at least a couple cleaning floppies around here, but they’re *OLD*. Zane