Chuck, Stuart and SACestria, thank you for the idea of buying a replacement strap, because yes, the failure of the snaps is on the strap, not the sensor. The female part of the snap, which is on the strap, fails by separating into two, with one part remaining stuck on the male part which is on the sensor. Sounds like Paul and Don experienced a similar failure.
I can see that replacement straps all seem to have a standard distance of 45 mm between the snaps, and the Bkool is +/- 1mm of that, as closely as I can measure, so substitutes should accept the Bkool sensor. Don has had good luck with an inexpensive Coospo
Also, Chuck and Tim, that’s a good point about rinsing the strap off. Though the snap seems to be stainless, corrosion could potentially be a reason why the female part of the snap separated into two. I do see some green oxidation. So, rinsing it more often would have been a good idea, although it would have meant unsnapping it more frequently.