Disassembled my entry door window today. Used a utility knife to cut, and then a razor blade scraper to clean the old spacer off. Spacer and sealer is on order now. I do have welding argon in the shop and have thought about running a needle inflater with argon running through it into the gap in the spacer at a low pressure/flow rate while sealing. I love the vibrating tool idea. I will try that on my next one, although this one was kind of easy because of its size.
The hardest part for me was getting the frame apart. The screws were sealed over with a very durable sealant, which was tough to get off to expose the screw heads.