I don't care that much about the 510 pin, I doubt any of them are completely leak proof under all circumstances, and when the topper is actually affixed to the 510 pin, I think there can be a certain amount of leakage. The statement above is what I take issue with, since "I used it until the board just stopped working," is never a good thing. It's also possible the OP was screwing on his tanks too hard, causing problems with the pin, etc., given that this happened to two mods in a row, I'm either going to blame the tank (which if the tank is leaking, the user needs to do something about) or User Error here, where the tank wasn't appropriately affixed to the mod or something, in which case anything can leak.
The "I wonder why?" part is what gets me. Are you very new to Ecigs, Keyman? Because if I was voluntarily allowing waterfalls of juice into my mod, my question would be "Why is this sucker still working?" Not, "I wonder why." I don't think it's the mod, QC, or anything other than User Error, which is kind of nice, as it can be fixed. Maybe we should focus on that, now, I'm guessing.
Keyman, what tank are you using, did it always leak, what did you try to get it to stop leaking, what coils are in it, what type of ejuice do you use, etc. Just lay it all out there, I'm sure we'll all learn some things, hopefully helping you get to a better setup for you in the process!!!!
Anna