Hi Hugh,
did you check the event log of your server? Often you will see there more hints about disk issues (ntfs errors, damaged sectors).
If the server is running already for a while it may also be possible, that it collected a lot of dust inside, causing internal overheating of components and therefore random instabilities.
The normal way is to backup important data and after that perform a server reinstall, the exact procedure you should find in the manual of your device.
Replacing the disk and restoring from an image as you intended is something, which is not supported and only in a very few cases works (i.e. the disk ID should not change).
Best greetings from Germany
Olaf