Can I run FSCK interactively? (Or is it worse than that?)

This is a follow-up to:

viewtopic.php?f=24&t=74918

and

viewtopic.php?f=24&t=74972

To recap: My ReadyNAS NV was getting stuck 92% of the way through FSCK. I booted, skipping FSCK, and discovered that one drive wasn't healthy (Raw Read Error Rate, Read Soft Error Rate and Current Pending Sector errors were climbing). I replaced the ailing drive, waited for volume resync, and with no errors in the log file everything seemed okay.

But all is not well. TimeMachine running on my Mac is failing. A snippet of the console log follows:

1/25/14 5:31:17.230 AM com.apple.backupd[7698]: Mounted network destination at mount point: /Volumes/ReadyNAS using URL: afp://ReadyNAS@chimborazo.local/ReadyNAS
1/25/14 5:31:17.000 AM kernel[0]: AFP_VFS afpfs_mount: /Volumes/ReadyNAS, pid 7844
1/25/14 5:31:17.000 AM kernel[0]: AFP_VFS afpfs_mount : succeeded on volume 0xffffff80d8e3f008 /Volumes/ReadyNAS (error = 0, retval = 0)
1/25/14 5:31:42.576 AM com.apple.backupd[7698]: Failed to create backup of Time Machine Information file /Volumes/ReadyNAS/MacBook Poor.sparsebundle/com.apple.TimeMachine.MachineID.bckup, error: (null)
1/25/14 5:32:27.000 AM kernel[0]: jnl: disk6s2: replay_journal: from: 210067456 to: 212340736 (joffset 0x2ace000)
1/25/14 5:32:34.000 AM kernel[0]: disk6s2: 0xc005 (UNDEFINED).
1/25/14 5:32:34.000 AM kernel[0]: jnl: disk6s2: update_fs_block: error reading fs block # 44500856! (ret 5)
1/25/14 5:32:34.000 AM kernel[0]: disk6s2: 0xc005 (UNDEFINED).
1/25/14 5:32:34.000 AM kernel[0]: jnl: disk6s2: update_fs_block: error reading fs block # 44500858! (ret 5)
1/25/14 5:32:34.000 AM kernel[0]: disk6s2: 0xc005 (UNDEFINED).
1/25/14 5:32:34.000 AM kernel[0]: jnl: disk6s2: update_fs_block: error reading fs block # 44500860! (ret 5)
1/25/14 5:32:34.000 AM kernel[0]: disk6s2: 0xc005 (UNDEFINED).

... and so on for many screens.

I realized that I hadn't done a clean reboot since re-synching the volumes (recall that FCSK was getting stuck at 92% BEFORE installing a new drive), so I decided maybe I should run FSCK again. So using FrontView, I powered down the system with the [check volume] checkbox.

Many hours later, RAIDar reports that the file system check is stuck at 12%.

I'm concerned. Is there a way to run FSCK "interactively", so if there *are* uncorrectable blocks, I can mark them as bad?

WWAGD? (What Would A Guru Do?)

Thanks!

P.S.: I will head out to Fry's today to buy a 2TB USB backup drive -- I suddenly have religion and will do what I can to back up the data that's there.