Remove any broken, brittle or dried parts of the old glazing. Use a glazing tool to remove the remaining glazing compound. You may want to use a heat gun to ease this process.
Fix glazing compound into the crevasses where compound previously was in place. Apply the compound firmly against the window frame and slightly onto the low region of the glass for additional stability and to secure the glass. Use your scraper to smooth the glazing compound and spread it evenly across the frame joints.
Apply the glazing compound to the other side of the window the same way. Make sure you apply the glazing compound evenly and that it is is equal in height to the opposing side going up the glass.
Let the glazing compound seal for two to three days before priming and painting the window. After the paint also dries two to three days, you can resume regular use of the window.