"Coat holding groove in trimstrip with soap water and slip trimstrip starting from corner on pane."

"Push rubber cover on trimstrip aside and apply soap water all-around between rubber and body."

This is from 67-220 Removal and installation of ornamental frame on back window from MB service CD.

How thick should the soap water be?

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.