Playfield insert labels can be restored easily. Use clear 1 or 2 mil
self-adhesive mylar and print the letters on it using a laser printer, or a
copy machine. Cut out in the shape of the insert and apply. The only
disadvantage of this approach is that in some insert locations the thickness
of the mylar will affect play slightly. You will be better off to use the
thinnest mylar you can find.