chkdsk is basically used to check for HDD corruption by scannig for and attempt recovery of bad sectors on the HDD. ScanDisk
from the old MS-DOS days was replaced by chkdsk.
sfc /scannow is basically used to scan Windows system files for corruption or modification, and attempt to repair them by restoring them back with a clean default copy.
The problem may be that you have it connected externally instead of internally since it's a OS drive and you are trying to create a image of it.
You may just need to take ownership
and "Allow" your user account "Full Control" of the XP drive and/or files on it to be able to have full access.
However, you might check with the HDD manufacturer's website to see if they have a HDD diagnostic utility available in their support area for that specific brand and model. It will be able to help tell you if there is a problem with the drive itself or not.
Depending on what you are wanting to do with the XP drive, you could make a backup of anything that you do not want to lose on it, then format it to hopefully have it usable as a data drive if you like.