This flat black cable sits on the underside of the lid on your Glowforge. If it gets damaged, it can cause intermittent errors that make printing difficult. 
Instructions on how to replace your cable are here https://support.glowforge.com/hc/en-us/articles/360054009914-Replace-the-Black-Lid-Cable
Glowforge can take several weeks before they send replacement parts. We send out all our parts in 1 or 2 days and offer multiple shipping options including UPS overnight so you can get your machine back up and running as soon as possible.
Official Glowforge OEM part.