At a distance, this 1920's bungalow looks pretty good. What you don't see in this photo are the poor state of the windows. This house is suffering from years of neglect and poorly executed renovations. Ultimately, it needed mortar, knee brace, facia and stucco repair, but for this post I will concentrate on the window repair.
I began by scraping all the old caulking from the windows trim and even scraping most of the glaze from the windows. I used several tools to do this including: wood chisel, putty knives, and wood scrapers. It was a real mess for about a week.
Everything I read said to be sure and get all old glaze out before reglazing, but it would have been impossible. I would have broken many panes of glass that way. So, I just scraped the really bad areas and tried to smooth out the high spots. Glazing is apparently easy and quick if you are experienced, however It took me a week to prep and glaze 4 windows! ouch!