I was just timing my boiled egg the other day, and when I pressed reset, the second hand flew back and then fell off. Luckily, one of my neighbours is a retired jeweller and watch repairer and he sorted it out. He said he had to “nip” the tube on the second hand slightly as it wasn’t as tight a fit as it should be and kept slipping past 12 when he pressed reset. Anyway the watch is fine now and my boiled egg this morning was spot on.
Glad you got that "issue" fixed. I would give that watch a pressure test, now that it has been opened.
Never had the large second sweep hand go flying off on any chronograph I own. I have had them not reset to zero, I have had to push the reset button more than once to get the sweep hand to reset, but no flying off. I did have the AP logo pop off the top of the crown about a week after I bought the watch... AP gave me a new crown and the logo has not popped off in almost 20 years.
He did pressure test it. His test gear will only test down to 90 metres and the watch managed that OK.
Good that you got it fixed quickly. I had a (vintage)watch that I sent for service, and my watchmaker said that he suspected that the chronohand had been superglued to the stem. Superglue would of course keep it from falling off ever I don't think that is SOP anywhere, however.