Thanks so very much for your help!! I'm boggled by it and now just about ready to dump the whole idea of Time Machine and backup using a cloning program. Maybe TM is only guaranteed to work well with Time Capsule these days?
Today there again was no backup. I did as you suggested, looked into Console. It showed many lines of "(Error) DiskStore: No block in wakeup" and also repeatedly "(Warning) DiskStore: Ignored bogus fetch...".
So I created a marker and attempted to initiate a backup, keeping Console open and refreshed. Here's what I got:
8/19/13 5:18:40.385 PM Console: Marker - Aug 19, 2013 5:18:40 PM
8/19/13 5:19:48.844 PM com.apple.backupd: Starting standard backup
8/19/13 5:20:00.484 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.484 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.484 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.494 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.502 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.506 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.507 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.507 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.507 PM mds: (Error) DiskStore: No block in wakeup
8/19/13 5:20:00.507 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:37ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.507 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:37ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.507 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:37ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.507 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:37ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.507 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:37ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.508 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:38ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.510 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:40ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.511 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:41ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.511 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:41ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:00.511 PM mds: (Warning) DiskStore: Ignored bogus fetch for <MDSQueryWithBlockTask: 0x7fd15ce03400>{taskID:0x0000103a age:41ms} (not live not complete) _kMDItemQueryPath=418546
8/19/13 5:20:20.000 PM kernel: USBF: 58091.976 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:20:51.000 PM kernel: USBF: 58122.985 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:21:22.000 PM kernel: USBF: 58153.992 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:21:53.000 PM kernel: USBF: 58185. 2 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:22:24.000 PM kernel: USBF: 58216. 14 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:22:55.000 PM kernel: USBF: 58247. 25 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:23:26.000 PM kernel: USBF: 58278. 41 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:23:57.000 PM kernel: USBF: 58309. 51 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:24:28.000 PM kernel: USBF: 58340. 59 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:24:59.000 PM kernel: USBF: 58371. 68 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:25:30.275 PM xpchelper: for uid: 501 -- timeout while waiting on FSEvents flush; clearing cache.
8/19/13 5:25:30.000 PM kernel: USBF: 58402. 82 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:26:01.000 PM kernel: USBF: 58433. 96 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:26:32.027 PM com.apple.backupd: Backing up to: /Volumes/TMBackups/Backups.backupdb
8/19/13 5:26:32.000 PM kernel: USBF: 58464.112 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:27:02.653 PM com.apple.backupd: Error: (22) setxattr for key:com.apple.backupd.HostUUID path:/Volumes/TMBackups/Backups.backupdb/David’s iMac size:37
8/19/13 5:27:02.657 PM com.apple.backupd: Error: (22) setxattr for key:com.apple.backupd.HostUUID path:/Volumes/TMBackups/Backups.backupdb/David’s iMac size:37
8/19/13 5:27:03.000 PM kernel: USBF: 58495.121 AppleUSBEHCI[0xffffff800a927000]::Found a transaction past the completion deadline on bus 0xfd, timing out! (Addr: 7, EP: 1)
8/19/13 5:27:12.668 PM com.apple.backupd: Backup failed with error: 2
During this 9-minute timeframe Finder also was inoperative - according to Activity Monitor: "Not Responding".
I'm thinking it's the standalone Buffalo backup drive not waking up, and so everything comes to a screeching halt. Do you also think I should abandon TM and just do manual backups every day using a clone program?