MacBook A1342 Hard Drive Replacement Using the Hard Drive with Upgrade Kit
Computer very slow to respond.
Very well. PLease read alternate installation technique.
MacBook Unibody Model A1342 Hard Drive Replacement
1 TB SSD Hybrid 2.5" Hard Drive with Upgrade Kit
This procedure assumes your old hard drive still works, but is being replaced for greater speed or storage.
The existing iFixit installation guide, MacBook Unibody Model A1342 Hard Drive Replacement has all the information you need to physically remove and replace the hard drive.
However, the instructions at the end link you to an old process to install the OS-X via a boot-up disk for older versions of the operating system. Later versions of OS-X are only available via download. Google searches turned up several youtube videos instructing you to download OS-X to a thumb drive, use cloning software, and then transfer it to a newly installed hard drive.
Only certain thumb drives can be partitioned as required for OS-X.
A simpler alternative works well.
Forget the thumb drive.
Forget cloning software.
Backup as usual.
If you order a new hard drive with the upgrade kit, it includes the Silicone 2.5" Hard Drive Enclosure with USB 2.0 Cable intended for use with the old hard drive after its removal from your MacBook.
Rather than use a thumb drive, before taking anything apart, just insert the new hard drive into the enclosure, plug it into your computer’s usb port and then use your Finder to select the new hard drive (temporarily an external drive) and with your Disk Utility app, do the erase, partition, naming, etc, in preparation for installing OS-X.
See Installing macOS High Sierra for partition and volume format instructions only.
Then select the old, still-installed drive and download OS-X from Apple. When downloaded, it will ask you where to install it. Select the new (still external) drive and install OS-X there.
Once installed, use Apple’s Migration Assistant https://support.apple.com/en-us/HT204350 to transfer (copy) all your files from the old drive to the new (still external) drive. You can then use your Startup Disk app, see https://support.apple.com/en-us/HT204417 to select the new (still external) drive as your startup disk. Then restart the computer and it will then boot up using the new drive.
Then you can check function and content on the new drive to make sure things are as they should be. (Both drives should be identical at this point.)
Now you can physically remove the old drive and install the new one (removed from the enclosure), knowing that the new one is fully functional ahead of time.
Then put the old drive in the enclosure and you can keep it as a full backup or as just another external drive.