G-Drive 3tb partition issues

[button4]

Hi
I'm new to the forum so bare with me.

I have a G-Drive 3tb with 3 partitions, connected to my iMAC running 10.7.5 and yesterday
the drive started making strange repetitive noises. Today, it wouldn't mount and when I used the Disk repair utility to get to the bottom of the problem, I was getting a notice that the disk was 'Read Only'. I have run an individual partition verification and PT3 and PT2 seem ok but PT 1 has stalled at 'Volume bitmap needs minor repair for orphaned blocks'. The verification list has a lot of 'Invalid volume directory count' and 'Invalid volume file count'.

Any ideas as to what I can do?

regards
B4