Just an example of how I like to leave things original as much as possible. I am doing my Williams Flash restore http://aussiepinball.com/index.php?topic=11238.msg147155#msg147155 and most things are intact and authentic from 1979. Globes, rubbers and leg levelers were the only new components and everything else was cleaned.
An example where I could have put new decals are the drop targets and spinner. I cleaned and left the originals. The spinner was 15% worn to the metal at the base where I touched up. The targets are slightly worn. I put contact on all targets and the spinner to preserve what is there.