This can be a good way to get a feel for using checkering tools but only if the original work is well defined. Here are some suggestions for consideration. If there is finish in the old work, use a stiff brush with paint remover to scrub it out. Cut the shortest and the most worn lines first because they'll be obscured by the other recutting. On the shortest lines you may want to start with an Exacto knife and retrace the lines with a light cut before using a single cutter. A 75 degree cutter will track better than a 90 degree. If the checkering is badly worn, retracing it can be impossible. In that case, scribe in a pair of master lines and checker as if this were new work. In the process you'll erase the old stuff altogether. Good Luck.
