I think that in most cases you can just copy the old card to a new card. The damaged sectors are usually in the writable user partition, and those are not necessary for booting. After copying to a new card, you can run a filesystem checker on the writable partition to correct any errors in it before trying to boot the device with it. There is another thread in this forum with lots of details on how to modify the new card so that it boots; you will need to follow those instructions because a simple copy will not work by itself.
N.B. Do not do anything with your damaged card except try to read the data off. It would be best to read it once by ghosting the entire image to a file on your computer. Then copy that ghosted image to other cards or files when doing modifications. Do not try to write back to the damaged card, or you will just make things worse. Do not modify your ghosted copy because you may not be able to recreate it from the damaged card later.
Here is the link to the other thread:
https://www.mobileread.com/forums/sh...d.php?t=278728