Digital BW, The Print

I'm puzzled today with the appearance of a couple of problems with my 
1160 using MIS VM inks.

1) I've printed a purge pattern and it shows microbanding in the Cyan 
and Yellow patterns. The Black and Magenta look okay, very smooth. 
Does anyone have any idea about how to get rid of the microbanding?

2) Occasionally while making a print I will get large streaks of 
black ink on the left side of the print. The streaks have some much 
ink that the print is wet. Cleaning the bottom of the print head with 
a paper towel wicks a lot of black ink. Does anyone have any idea 
what causes this?

Thanks,

Don Bryant