The area of contact between the connector and the sear is so small that anything - rust, old grease, ice, grit - can cause it to fail.
In the literally hundreds of "Walker Triggers" that I've completely disassembled, inspected and serviced over my many years in this business, I've never found ice, rust or grit between the connector and the trigger lever. What I've found in triggers that haven't been "tampered" with, is old, gummy oil residue and preservatives surrounding the sides of the connector, holding it out of place. Routine MAINTENANCE and the use of a bore guide to prevent solvents and oils from finding their way into the trigger housing IS THE FIX for this.
But the clear majority of AD's that have made their way to this shop are the result of a lack of maintenance, along with reduced sear engagement and reduced trigger spring settings, caused by tampering with the factory settings by folks who don't know what they are doing.
