I don't like how DMT is lapping hard and fine grit stones.
I'd prefer to lap with set of silicon carbide (SiC) powders up to 1200 grit with just sheet of glass on some flat surface. Or with ceramic plate.
Use some water to make a slurry with SiC on glass. Distribute it evenly. And use 8-like motions for lapping.
Here it is on video:
Как править японский точильный камень - Мастер класс по заточке ножей - YouTube