the coupler teeth fell off the base of my kitchenaid blender, how do i stop that from happening again?

You removed the jar or pushed the lid while the blade was spinning. The force shears the coupler teeth off.

1. Always press the stop button and wait for the blender to come to a complete stop.
2. Unplug the blender.
3. Then, and only then, remove the lid or jar.

If that didn't work, check your blending technique for frozen items. Blending chunky frozen fruits immediately at high speeds causes wear on the coupler. Use the pulse function first to break chunks.

Heads up: When moving the blender, lift from the base. Carrying it by the jar or jar handle will disengage the base and can damage the coupler connection.