A persistent buzz was emanating from one of the external hard drives. When it was (carefully) inspected, the buzz became an alarming repetitive clang after turning over the drive. Thankfully the TiVo—and therefore presumably the drive itself—was still working. Which meant it was probably the fan.

We turned everything off and tried to clean any residual dust that might be contributing to the nasty noise, but the best we could do was get it back to a (noisy) buzz. I assume a less-than-optimal fan performance could lead to overheating of the drive itself. How urgent is it that I get this addressed, and in what way exactly? Thanks for any answers.