Please see the attached Tech's Corner article Troubleshooting Slack Cables. This article was created for beginning troubleshooting, to provide a check list for what to check for initially. Slacked cables can result from various issues from track being unlevel, a door unshimmed with unlevel flooring, cables being slightly different lengths, to EZ Set Springs being compressed or garage door opener issues. This article was designed to point out common issues to narrow down the cause and identify the source of the issue and provide possible resolutions.
If the issue is still unknown, pictures and complete order details are required to inspect further.
For more information, please see Tech's Corner: Introduction to Jackshaft Use, Pusher Springs and Cable Snubbers.