To overhaul an older style freewheel hub you must first remove the freewheel mechanism. As is usually the case with older bike part designs, it needs to be checked more frequently than a modern sealed cartridge design. but if you look after it carefully, it can last a very long time.
This is a long guide, so you can choose to either watch the entire video above, or follow it in smaller chunks by clicking on the individual steps below.
Steps to Overhaul A Freewheel Hub:
A freewheel is a ratchet mechanism mounted on the rear hub which allows the chain to drive the wheel forwards via a cog but when the wheels move faster than the chain the cog is not driven round by the wheel. A freewheel allows a rider to rest their legs while the bike is moving forward.