Repairing fogged windows

I feel that the QC is lacking during the window manufacture. The instructions that come with the window seal/spacer states to seal the package between usages, and I get the feeling that they do not pay too much attention to how long the seal is exposed to normal air. From what I have gleaned from the Web, these windows should last at least 10 years, with no problems at all. When doing the rebuild, a 1 hour limit is imposed on the seal, being exposed to humid air, not sealed. The first Dave Root kit, ($280)cost me right at $80 for the seal and the urethane sealer. Ace Hardware has a silicone sealer, that sets-up to a plastic like sealer, just like was on the windows when I removed them. I have tried the original seal, and butyl rubber tape, but did not get the result that way required. Once you have done a couple of windows, the hardest part of the job, will be getting the window frames apart, to get the glass out, and back together, after doing the window panes.