The clipper part referred to as the lever, blade drive, or swing arm is by far the most important part of any clipper. A worn out drive part can cause new and re-sharpened blades to seem dull. As a drive tip wears it actually shrinks in size and can cause the blade to cut poorly and leave lines in the coat. You may also notice that your blades will chatter or run noisy, which is another sign that the drive part needs attention. Be sure to change out the drive mechanism on a regular basis as needed.
This video demonstrates what to look for, how to access the blade part, and how to replace it on two of the most popular clipper types in the industry.