This happened yesterday morning -- After I reached about 50mph (80kph) my
speedo started an awful racket (humming/screaming/grinding) and increased
indicated speed -- to the point that it pinned on the highway.  I got
concerned and disconnected it.  Later in the day, I reconnected it, and there
was no problem.  I'm assuming some lubrication problem because of the apparent
correlation to temperature.  Cold weather has arrived here in SE PA, and
though yesterday (and again today!) temps reached the upper 60's (+/- 20C for
the rest of the world), early mornings are in the 30's (1 -2C).
Any ideas about what's going on inside my speedo, and more importantly, how to
remedy?
TIA Doug