I have been hoarding metal Salomons for a long time, in anticipation of my little project. And I've been grabbing every Salomon wormscrew metal heel (steel track) I see at thrift stores, even if they come with a plastic toe (DIN=14). The steel track (wormscrew) heel seems to work reliably no matter how old it gets, and I'd just retire them before catastrophe if I ever see the heel wiggle/looseness getting way, way bad. For toes, the metal toes seem reliable no matter how old they get, unless you can see obvious loose toe wing wiggle, or if the toe wing adjustment screw gets loose frequently and needs to be retightened every day, etc. I prefer not to use the Salomon plastic DIN=14 toes, but I've never seen one fail catastrophically, because you just retire them when you see obvious warning signs, like toe wings getting loose every day, etc. Honestly, I don't know if the DIN release values are still accurate on any of these old bindings, or need to be recalibrated, but they hold me in, and I've never had a problem.
A few less common versions of Salomon's DIN=14 bindings had the common low-end weak alloy heel track with tab adjustment (not wormscrew), but with a strong metal heel cup...although that heel had other plastic components that can break with age. I have always rejected those, because that weak alloy tab heel track can break with age, or the plastic slider in the track can break. However, I'm starting to consider using some of those on my least favorite skis in the quiver (which I might ski only 1-2 days per year), because I can "create" pairs of those metal heel cup bindings by mixing and matching parts at the thrift stores (like I could harvest metal-heelcup sliding tab heels from the unpopular Salomon ProPulse DIN=14 bindings, and slide them into any common Salomon DIN=12 alloy heel track). Etc.
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