ML 10.8.2, Disk utility says external TM partition is good. Fresh reboot, Activity Monitor says 90% idle
TM backup is taking long. It is getting stuck at 220MB for a long period of time.
After disabling File System Shield of Avast 7.0 (37682) current release and restarting TM backup it is moving a bit faster, now it is backing up 1MB (not GB) every 10 seconds, still very slow, but much better than forever.
I hope this helps