Fridge door not closing, black dust on floor

For the past few months, we have noticed a bit of black dust on the floor where the "hinge" is located on the bottom right of the fridge door of our side by side unit. Lately, the door does not close all the way when you push it and frequently requires an extra "push" to be sure it is sealed and closed. Also, there is black "dust" on the floor on the lower right. I have researched an am thinking it’s the door cam, but want to be sure. Also, do we replace top and bottom? Which parts do I need?
Michelle

Here are your parts
http://www.appliancepartspros.com/partsearch/modelsearch.aspx?model=GS6SHEXNL00

I would replace both of the cams on that hinge.
Item 10 in section 06 and item 26 in section 01.

Item 26 in section 01 does mention a kit that includes both but when I input your model number it says that it is not compatible with your unit so I would just order the individual parts unless a parts person can confirm the kit will do the job.

A light coating of grease on the rubbing surfaces may reduce wear.