UPDATE: Now the speedometer and odometers have failed completely. The speedo is stuck at zero and the odometers don't advance. But at least the annoying noise is gone.

QUESTION: Does the speedo cable run anywhere near the ATX dipstick? Yesterday before the speedo started failing, I had checked the ATX fluid. It's a tight reach in there to the dipstick between some cables and tubes, but I can't imagine that I could have damaged it just by reaching through there. That would be a pretty fragile cable if so. Any ideas?