Old timer told me I was wiring my connectors backwards, and he was right
I was working on a Cessna 172 last Tuesday and this 60 year old mechanic walked by, stopped, and just goes 'You're feeding your pins backwards, kid.' I mean, I'd been doing it the way my instructor showed me for two years. Crimp the wire, insert from the back, pull the test. Turns out he meant I should be seating the contact from the front of the connector housing first, then pushing the wire in. It sounds dumb but it stopped my pins from backing out when I did the pull test. Now I get better continuity checks and way less rework. Has anyone else had some old timer correct a basic habit that you thought was fine?