My Seagate FreeAgent external drive has a problem. It's several years old, but still has over half capacity. Not sure if it's half empty or half full (joke). Anyway, I get this message that Time Machine cannot connect to the current back up disk. I've tried turning everything off and back on again. I also went into Disk Utility and tried to do some first aid, but got a message that updating boot support partitions for the volume as required. Unable to unmount volume for repair. Operation failed. Is my Seagate fried? Any suggestions would be appreciated. I can't afford a new one right now.