Lenovo ThinkPad T420 Hard Drive replacement with SSD

Replacing the Hard Disk Drive (HDD) with a new Solid State Drive SSD (or another HDD) in the Lenovo ThinkPad T420 only requires the removal of one screw to take out HDD caddy, then the four screws that hold the drive on the caddy. Try not to overtighten the screws. An original HDD may have adhesive tape holding it to the caddy, you can get this off quite easily (but it's not shown in the video as my drive had already been previously replaced).