[cspm]

Thanks for your quick reply.

However, I seem to have solved the problem.

I booted up on the iMac itself (instead of from an external drive) and clone the drive where the iMac system software is found. Was all done in just over an hour. (it seems you can only clone the drive you are currently running?)

I am using it now.

But originally, I booted up on an external drive and clone the iMac drive on to another external drive. But it just kept on running for over 9 hours and seems to be stuck at the point where it was copying the Library Folder. Just seems to have no progress from there. So it cancel, but does not work , so I do a force quit instead.