QUESTION My laptop hard drive is failing. I can still boot to the recovery partition but I'm unable to re-install the operating system. If I put the original hard drive into an external USB enclosure, put a new hard drive into the laptop and boot via USB to the original recovery partition could I then install the operating system to the new hard drive? (See also: How to fix an unrecognized USB drive.)
HELPROOM ANSWER The method you describe is likely not to work, as you'll probably find the laptop is unable to locate the recovery partition when connected externally via USB.
We would suggest you go ahead and purchase a USB drive enclosure and a new internal hard drive, but rather than attempting to boot from the damaged drive via USB, put the new hard drive into the external enclosure and clone the failing drive on to it using software such as Macrium Reflect. To do this you will first make a bootable USB flash drive using your cloning software and boot from that.
This cloning procedure should give you an idea of whether the recovery partition on the failing drive still contains valid data. If the procedure completes successfully, you should then be able to install the new drive in the laptop and perform the recovery boot from there.
Of course, there's a good chance that the recovery partition will have been damaged in which case you'll need to go back to your vendor for a recovery solution or install from any discs provided with your laptop. (See also: Remove an old hard drive and add a new C drive.)