That part is called a tension arm. They went out years ago when they discontinued the HS/15 plotter. That plotter ran too fast to pull media directly from the roll holder. When they discontinued the plotter, GSP still had a bunch of tension arms, so they shipped them with the Edge for a while.
If you really want better performance from your Edge, with no babysitting, wrinkling of media, and minimal dust spots, check out the GMS Heavy Duty Rewinders. Some people think they are expensive, but not when they count all the time & media they have wasted over the years. Here's a video to show you what I'm talking about:
[video=youtube;KSYLQG4si-0]http://www.youtube.com/watch?v=KSYLQG4si-0&list=UUluTjMklixHGGgjf77c-oXg&index=1&utm_source=GMS+Info&utm_campaign=ea113 1f027-Rewinder27_8_2014&utm_medium=email&utm_term=0_0117 5ee904-ea1131f027-[/video]
Doug Goodloe
Graphic Marking Systems
800-232-8018