ORIGINAL: CP140
One thing that works if you have a small dent/ding in balsa, is to fill an insulin syringe with water and then inject a small amount of the water into and around the dinged area. Then set your covering iron on "hot" and iron over the area. It will steam and swell the wood up again and take out the minor dings.
This method is especially useful once the model is already covered and you get small dents and dings from normal use and handling. It lets you get the ding out without having to strip off the covering.
Ken