So some updates. I contacted 3M and they said that the 08008 (black) and 08001 (yellow) are the same and that they only differ in color. I ended up getting the yellow just because it was different... I also realized that the tube of black I had was likely at least 10 years old. Sure enough, I tried the new tube and it's a much stronger bond. Will see how it holds up over the next year, but I think having a fresh tube was the ticket.