too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Looking at the photo, it appears to be a "cold joint". By that I mean that the crown and base of the steerer weren't complete heated to the proper temperature for the braze to flow in and fill the joint. If this were a sweat soldered copper plumbing joint it would have leaked, but it's hard to spot this in brazed bike joints until they fail.
Cold joints are more common than most would like to believe, but are proof of the amount of margin of error in classic brazed construction, in that most hold up way longer that you'd expect.
When I first started in the bike biz many decades ago, we had a run of track forks with this problem. Since there's no brake bolt to provide a safety net, we went to great lengths to track down and replace all of them (this was before product recalls were common). After that we insisted that the builder drive a pin into all our track forks prior to brazing.
IMO it would be more expensive to repair than to replace with a new fork, especially because the crown flexed open making for a poor fit.
It actually was a hand-made fork. It's from an early 80s Pogliaghi. I'm not really sure how it happened, I had locked up a my bike against a fence, and there was a bit of torque; handlebars pushing one way, front wheel pushing the other. But I can't imagine doing that would have caused the damage; it wasn't that much force, and I would have thought the stem would slip first.
After that had a pretty smooth ride from Greenpoint to South Brooklyn. No unusually large pot holes or anything. Steering was feeling a little sloppy, but I didn't notice how bad the damage was till I got home. Thank goodness the brake bolt was there holding things together!
Really surprised to hear that it was shoddy craftsmanship. My impression of Pogliaghi was quite high...
"It actually was a hand-made fork. It's from an early 80s Pogliaghi. " <--- do you really think these guys were producing 2 bikes a day back in the 80s?? Sorry for raining in your parade man but back in the 80s was like the boom of cycling production and the QC in several brands was pretty bad because they needed to get the bikes off the factory fast.
Yes the fork was hand made in a jig with tubing cut in less than 30 secs and brazed in 10 secs more. Probably took them no more than 15 mins to get that made and they made maybe 100 to 400 forks a day. And pretty much all the forks are made the same way, one guy cuts the tubes, other guy puts the stuff in the jig and braze it. And next day was going to chroming.
Sincerely that you get good stuff doesnt mean that the fabrication process takes 2 weeks as any hand made american frame. Technically they could made a frame a day but in factory made frames they made zillions per day. That's the cruel reality.