NV+ problems

Wow 16 hours to run an extended check in Data Lifeguard! So I got the 3rd out of 4 disks and the extended check failed - saying too many corrupt sectors to continue so I have my culprit. I have therefore removed the failed drive and replaced it with a new one. In RAIDar the NAS shows as running a File System Check. It also says it is running a resync that will take 77 hours to complete! Is it trying to run the FS check and the resync simultaneously? or will it wait until the FS heck has finished before starting the resync? Also do you know if there is any chance of what has happened here corrupting my data? I have thousands of files and no way to verify them all. I was thinking about just doing a factory reset and restoring from backup? Would love to know your thoughts!