how can i fix washing machine, whirlpool heavyduty supercapicity plus?

That was not black soot, it was black rubber. Your motor coupling is torn up. It's an easy fix if you know what you're doing, but I suggest you find a service person or some one who knows how to repair it. To get to the coupling you need to take off the cabinet, then the pump and then the motor. Sounds more complicated than it actually is. Good luck.

Jennifer Ott, Good Appliance
April 2008