Why won't my Whirlpool (model # LSN1000KQ0) washer agitate at the low speed?

My whirlpool washer (model #LSN1000KQ0) was making loud noises about 2 weeks ago. I pulled out the machine and noticed all this black dust on the floor. I decided to replace the motor coupling. I was back in business but noticed it is still not sounding right.
As I was checking the agitator dogs (they look fine) I noticed that the machine only does high agitation (it does a good job at it and it spins just fine but still no low agitation.). So when in the delicate cycle or Perm press cycle it just makes a clicking noise.
Also after 7 loads with the new motor coupling there is more black dust under the machine.
Why won't the washer do low agitation and where is this dust coming from?