I have the same problem, interestingly enough I have wired these fans the heatsink and put these grills on them and they've lasted way longer than the metal cased RC fans have. They don't spin as fast either but are enough to keep the motor cool, I've measured temps they are fine. Shit, maybe it's the lower rpm that is making them last as they do.

It took some work to splice it all together but now I have fans that have lasted and are pretty colors for the night sessions I go to 😁

Edit : fixed links