How to replace the existing coupler.

Just pull out the existing disc-coupler from the grinder and insert one-touch coupler with leaf spring facing up. Screw the washer tight with the wide leaf side facing up

To detach BTK coupler from the grinder, hold the grinder’s lock with a finger and turn BTK disc counterclockwise a little strongly until the washer is loose

How to load/detach BTK disc on the grinder.

Hold the grinder’s lock with a finger, insert the BTK disc and turn clockwise to tighten, or turn counterclockwise to detach