broken glass in kenmore dishwasher
 

Hi: a glass broke in our dishwasher and there are chunks of it inside that I need to get out. I've removed the bit shown in the first picture. But I can't figure out how to remove the filter (?) shown in the second picture. The bolt/spindle in the middle just spins, and I can't hold the black plastic bit hard enough to loosen the spindle. Any suggestions? Thanks a lot. Simon