Corrupt parts will automatically be tried to be recovered/repaired. If the file completes 100%, then all corrupt parts were successfully recovered.
If a file is not available 100%, then it's not possible to complete. Well, unless a source comes online that has the missing parts. You can check the "Last Seen Complete" column to see if aMule has ever seen the complete file available. If that is the case, it might worth waiting for sources - however, it's always your decision how much you will wait for a file to complete.
