The glass is fixed into a rabbet in the frame in a number of ways including triangular
glazing points, putty, etc.
Make sure to remove any staples, nails, or
glazing points used to hold the glass in place.
Also buy a package of
glazing points ($2) to hold the glass in place while the new compound hardens.
There's no need for
glazing points. To nail the moldings in place, you can carefully drive in tiny brads with a hammer or carefully shoot in brads with a pneumatic brad nailer.
Other materials--sandpaper, glue, lacquer, putty, glazing points, eyelet and wire--will add up to about $15.
SECURE the picture by pressing glazing points into the sides of the frame with a stiff putty knife.
Under the compound, you'll find tiny metal tabs called
glazing points. Yank them out with pliers.