Pull Rope Broke on Murray Lawn Mower, how to replace?

[Microman]

I look at the location of this 18"? mower pull motor, and I started to take off the top. There is a small removable circular piece that snaps off, but the vented area that covers the retractable rope, is held down with permenant connectors. Not screws but rivots.

I can't figure out how I would either replace this rope that came loose, or buy another to put it on.

Has anyone every worked on a murray mower model 21661X28B?

Thanks