I haven't experienced this before and don't know the potential outcomes. Thank you for clearing that up.

Any reasoning as to why alarm 105 has disappeared and 163 is now present?

I realize you seem certain that it's the drive, and I'm thankful for your advice...but I've also spent a considerable amount of time reading a lot of other threads on this very issue and there seem to be a few other possibilities I need to check off the list.