My light never worked either, and I bought the unit new from a dealer -- if you're talking about the Gyro SE. But, you'd have to be pretty drunk not to see the platter spinning, what, with the dangling gold weights and all... :)
That said, the light does light on my Orbe SE, which is a lot harder to notice if the platter is spinning, even if you're sober.
Certainly the light does not make the speed any more accurate (possibly the reverse).
