I've found that some computer CD drives are much better at reading
damaged discs than regular CD players. Try ripping them into the
computer at the lowest possible speed -- ideally 1x, but I've found 2x
often works. You may have better results on a Windows or a Linux machine
than a Mac.
I use a TDK CD-R burner, which reads very well, and Audiograbber for the
ripping software. About the latter, you have to do the Settings each
time you rip a disc, to select the destination directory and to select
the rip speed. If you don't do the latter the software will default to
maximum speed, regardless of what's selected, a minor bug in an
otherwise excellent program.