How to know when your clipper's blade drive needs replacing
One blade set is made of two blades, one that moves and one that stays still. The blade drive moves the smaller of the two blades side-to-side, thousands of time a minute. When the smaller blade slides across the larger blade, the blade teeth act like multiple tiny scissors, and they cut the coat.
The blade drive WILL wear down, faster than you might think. The blade drive (and blade latch), should be one of the most frequently changed parts in most clippers.
What are the signs of a worn blade drive?
A worn blade drive causes a number of common blade and clipper problems, such as reduced blade performance and leaving blade track marks (like corn rows or a corduroy pattern), in the coat.
These problems can be caused by other factors also, like a dull blade or impacted fur blocking the blade drive from making the full side-to-side motion. So if you have a blade that is 'chewing' the coat or leaving track marks, ideally test that same blade on another clipper first to find out if it's the clipper or the blade. Whether you can test it on another clipper or not, thoroughly clean the blade, the blade drive and blade latch, and test the blade again, before replacing the blade drive.
Simply cleaning your blades after every use (or at least once a day), and removing stuck fur from the blade drive and blade latch (at least once a week), can significantly help extend the life of your clipper. Hair will otherwise work its way inside the clipper housing and motor and become impacted over time, causing potentially serious issues.