Removing shellac is one the easiest types of wood finish repair jobs.
Blotch Control to Rule Them All - The Wood Whisperer
5 Simple Ways to Fix Scratches on Your Wood Furniture - Lost & Found Decor
The Best Way to Clean a Shellac Brush – Bob Rozaieski Fine Woodworking
How to Guide for Stripping Furniture the Best Way • Refresh Living
How to Fix Furniture Finish - This Old House
Four Common Finishing Mistakes (and how to avoid them)
How to Remove a Shellac Finish - FineWoodworking
The Best Way to Fix Chipped Wood Furniture
Restoring a Shellac Finish - Paul Sellers' Blog
How to Refinish a Cedar Chest