How To Release Tension on a Clipper Blade
Most blades normally jam because the top blade is too tight. If the top blade does not easily move backwards and forwards then clippers with a small motor will be unable to drive it.
To release the tension, place a flat head screwdriver under each side of the blade and gently elevate up, making sure the top blade does not come out of its guide. You should now be able to move the top blade easily.