Short answer. Andersen identifies a bulb-style weatherstrip on each of the four sash sides for 1978–2019 400 Series Perma-Shield casement and awning windows. For this range, its service article says to press replacement weatherstrip into the cleaned channel with no adhesive. A lifted strip should prompt confirmation of unit vintage, its mounting leg and channel condition—not a guessed glue repair borrowed from the earlier 1966–1977 adhesive procedure. [S:AND40078] [S:AND400OLD]
What can be checked without declaring the cause
A strip that protrudes or comes loose does not diagnose itself. Possible observations include a loose mounting leg, visible channel debris, an interrupted section of the strip, or a sash that does not shut normally. The manufacturer page supports a cleaning-and-channel press-in method, but does not publish a field diagnostic flow that separates every possible defect. Photograph the symptom rather than assigning the cause.
| Inspection record | What to capture | Do not conclude |
|---|---|---|
| Unit identity | Series, casement/awning, verified manufacture range | That every 400 replacement has identical mount |
| Seated area | Cross-section and location where strip is retained | Universal profile match from bulb diameter alone |
| Lifted area | Channel plus mounting leg, no forceful prying | Adhesive will fix an unverified mounting problem |
| Corner and ends | Full sash edge photos and where pieces meet | One-piece continuous replacement is automatically same order number |
| Closure | Whether operating sash closes and locks normally | More compression is always better |
Choosing the right service-document branch
If the window actually belongs to the 1978–2019 documented configuration, the Andersen replacement description calls for removing the sash, cleaning the exposed channel with mild soapy water, and pressing the correct part into place without adhesive. It also recommends replacing all four pieces when using separate seals and describes a one-piece alternative. [S:AND40078] If identity points to 1966–1977, stop here and use the separate legacy service guidance, because the adhesive instructions are materially different. [S:AND400OLD]
The manufacturer additionally describes a continuous one-piece replacement for 1978-to-present 400 Series Perma-Shield casement/awning units. That is not an instruction to stretch an old four-piece profile into a continuous loop or to change installation geometry. [S:AND400ONE]
What to send the parts desk
Provide overall window photos, product identifying code/era, the side from which the seal keeps lifting, close-ups of a firmly seated location and the loose location, and any known original part package. Ask: Is the existing strip the correct part for this sash? Is the mounting channel intact? Does the unit require the four-piece or newer one-piece order? Is professional sash removal required? An unknown answer stays unknown until the manufacturer or service provider checks it.
What not to do
Do not glue a strip into an unknown sash channel; do not force thicker rubber into the edge, remove the sash without suitable support, or promise that new weatherstrip cures sagging, lock resistance or frame distortion. A service visit is appropriate when the window will not secure, when glazing/frame damage is visible, or when safe access is not possible.
Evidence
Manufacturer Andersen Help Center 000002456 (1978–2019 bulb, Install Parts) and 000076881 (1978–present continuous replacement, Details); contrast Andersen 000005067 (1966–1977 Installation). All checked 2026-10-12: 1978–2019, continuous, legacy. Separate diagnostic intent from accepted NW0018's format comparison; only keep as new page if final editor confirms distinct search utility.