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Project Management Suggestion
It's helpful to have system administrators use the link checker tool in LibGuides before you start the remediation process, and then several times through out the project. Identify if there are links that project admins can fix in bulk to help, say to resources in the catalog.
There will be links that won't get picked up by the link checker tool because they do go to a live page, but it the destination may have changed or be outdated, so it's worth having humans double check the work.
Some authors are going to have lots of links on their pages and doing the manual checking for that can be daunting/demotivating so having a helper pool lets them focus on more difficult work.
Link checking is a task that can be given to anyone, they don't need to have a LibGuides account. It's a good downtime activity for student workers or other folks colleagues who aren't LibGuides account holders. Bad links can be recorded on a spreadsheet and shared with guide owners to fix.