Dual-pane windows: replace or repair?

Homeowner seeks cheap fix for leaky cells

Q: I've read your recent column about windows and have some related questions. I have dual-pane windows whose cells have "leaked" and the inside surfaces are discolored. They are installed in traditional wood frames and are easy to remove. They have a metal/plastic composite spacer frame at the edge, sealed with some sort of black mastic. I have a number of cells that were replaced under warranty when water leaked inside and would like to see if I can rehab them. If I can remove the spacer from one side, I could then clean the inside surfaces. Would isopropyl alcohol be a good cleaner, or would you advise something else? Then, how would I ensure that I remove all possible water vapor before I reseal the edge? By moderately heating the cell? Or by injecting some type of gas? I would reseal with some type of mastic. Then I would put a layer of sealant all around the perimeter to try to plug the original leak. Buying new replacement cells costs a bundle, and I have ...