He has closed his business within the past month.

Craig Zeni
Cary NC

Their groups.io site is still active, and there is discussion over there including about possible substitutes.
Apparently someone named Eric is trying to produce lost-wax brass versions of some modern designs in China,
and another person named Chris trying to pick up the original line,
but there's very little detail & nothing from or about Frank, the owner.

Tom E.

This has been discussed on trainorders.com for the last couple of days. Here is a small screen capture image of the closing announcement that someone posted from the Sergent web site on 8/12. It's just an image so the highlighted link in it is not clickable. Someone noted that the Sergent designs are (intentionally) in the public domain. I see the web site is now "parked".

Tom Madden

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Tim O'Connor
Sterling, Massachusetts

Yeah, been watching this carefully as I have over 120 cars/engines with Sergents.  Long story short is that Frank changed interest directions awhile back and has been wanting out of the hobby business, even offering his designs and initially the equipment for free.  He stopped making the specialized sand-cast couplers, but kept the basic HO type E's in production, which were nicely die-cast, while waiting for someone to pick up the line.
The only serious contender came from China, Inventive Model Works, a smaller firm that makes models and parts including brass investment castings. Eric Xing reversed engineered the Sergent (what Frank was wanting to happen) and produced a run of jewel-like preassembled versions.  His intent was to investment cast the unique stuff while Frank or Frank's replacement made the bulk quantity conventional couplers.  They sold out quickly, but Eric put it on pause while he finds a better way to ship them from China as Speedpak is unreliable and has no tracking ability. 
The big mystery is what is going on with Frank and his diecast equipment.  There are a couple of individuals who are interested in keeping that part going (to the benefit of all), but there appears to be unknown issues going on there. And of course, Frank went on deep radio silence awhile back.
Most likely all this is going to work out eventually, and progress is being tracked on both the Inventive Model Works and the Sergent Engineering Facebook groups (the only real use for Facebook).
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RJ Dial
Mendocino, CA

I just noticed, a week or two ago, that Andy Reichert's Proto:87 Stores web site has a page devoted to the die cast Sergents, but no ordering data: http://www.proto87.com/HO_Proto87_true_scale_couplers.html  This would seem to be a good fit for Andy's line.

Dennis Storzek