There are major problems booting USB drives so this method is not a solution for drive failure on your laptop. If you want to be able to restore partitions then use clones as image files and not as cloned partitions. BiNG or DriveImage or Ghost would be the sort of applications to do this. BiNG should have no problem with USB2 external drives (you may or may not need to enable its specific USB2 option under its settings if it doesnt work straight away) on a modern machine. Nor will BiNG be daunted by actual size of your large drive.I prefer cloning because a cloned drive can usually be booted up when the main
I suggest you repartition and reformat the external drive since you are having problems accessing it properly at the moment. If the problems persist check the drive with the maker's diagnostic utility and consider writing zeros to the drive.