There's a 'touch' to cutting or chasing threads. You don't want to obliterate the old ones, 'cause there won't be any metal left for the new. Then you have to go oversize with the threaded inserts, but can still use the original-sized hardware. The inserts, if you need to go that route, will specify the size drill and tap on the packaging.
When chasing threads, you want to turn 'ahead' 3/4 or so turn, the back 1/4 turn. Repeat.