Mac – Problem enabling journaling in order to resize partitions on an external drive (Mac)

So, heres the situation:

I have a 500GB external USB hard drive that is formatted with the GUID Partition Map and has 2 partitions, both formatted as Mac OS X Extended (Journaled). one partition, TEMP (~120 GB), is barely being used and I have moved all data off it for this. However, the other partition, MAIN, is being used for backups and is about 320GB and is already mostly full.

In order to avid having to spend hours and hours creating a brand new backup after formatting the drives, I found out that you can apparently resize partitions on disks that are formatted the way I have them. Which is great, except I can't increase the size of the MAIN partition because of the following error:
The volume “MAIN” is not journaled. As a result it can not be resized. To enable journaling, cancel partitioning and use the “Enable Journaling” command under the “File” menu.

I have verified and repaired both partitions numerous times with nothing bad coming up, everything is normal, however, when I go into terminal and try and manually enable journaling like it says, i get this:

 diskutil enablejournal disk1s2
Journaling was already enabled for volume MAIN on disk1s2

 diskutil disableJournal disk1s2
An error occurred journaling the file system: The underlying task reported failure on exit (-69860)

So it thinks journaling is already enabled… bit it thinks its disabled…. and i can't turn it off and back on again to test if that works… can someone please tell me what I'm doing wrong?

EDIT: While the drive is our primary backup drive, the backup partition has been full and no backups have been completed since July so I will probably end up formatting the drive anyway, but would still be interested to know what this issue is in case anyone else has this issue.

EDIT 2: here's the diskutil list info for the drive:

/dev/disk1 (external, physical):
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:      GUID_partition_scheme                        *500.1 GB   disk1
1:                        EFI EFI                     209.7 MB   disk1s1
2:                  Apple_HFS MAIN                    380.1 GB   disk1s2
3:                  Apple_HFS TEMP                    119.5 GB   disk1s3