This is an interesting thread.
Even with a UPS I was having difficulty with missing recordings due to power glitches. I finally recopgnized the pattern every two weeks on a Monday I would lose my cable input to the Tivo.
It turns out that my cleaning lady was unplugging items from my ups for the vacuum cleaner. I add a simple note over the plugs, the issue has been resolved.
A new HDD may not be a bad thisng to get for your system, especially with the lifetime service subscription.
I may be replacing my current drive, I've noticed that it will pause every once in a while.