At some point, all adjustable clippers will need to be cleaned and oiled for routine maintenance so that they perform as they did when they were new. When the blades don't seem to cut hair as easily or make a loud buzzing noise when the clippers are turned on, they may need to be removed and cleaned thoroughly and re-adjusted.
Turn off and unplug the clippers.
Look at the bolts that fasten the blades to the clippers so that you know whether to use a flathead screwdriver or a Phillip's head screwdriver.
Twist the bolts counterclockwise to remove them and put the bolts and the blades in a place where they can't get lost.
Clean the hair out of the clippers with a dry cloth. Do not use water (you may damage the electrical components inside the clippers).
Wipe the hair off the clipper blades, first with a dry cloth and a small brush for cleaning clipper blades and then with alcohol.
Replace the clipper blades, making sure that the teeth on the top blade aren't evenly matched with the teeth on the bottom blade. The uneven teeth allow them to slide back and forth to cut hair.
Turn the clippers on and lightly oil the blades. Too much oil will cause the blades to stick, but just enough oil will keep them going until the time comes to adjust the blades again.