Repair Disk successful boot support partitions not updated
I ran Disk Utility Repair Disk on a 2TB WD MyBook Studio II drive that stopped mounting to my mid-2010 MBP running OS 10.10.5. The report says the drive was repaired and is "updating boot support partition as required". Nothing further seems to happen and still the disk will not mount. Is there something else I'm supposed to do to complete the repair?
MacBook Pro, OS X Yosemite (10.10.5), Disk Utility