Hello, I have a C3 index board with the optical sensor, a CD painted black with a single 5/16 or 8mm slot.  When I position the slot in the sensor the index led lights.  When I rotate the spindle very slowly, the index led lights.  If I rotate the spindle quickly, the led does not light up.  When using Mach, it shows an rpm that seems accurate, and stable.  But when trying to cut a thread, it doesn't work at all.  When the spindle is rotating around 200 rpm, the led won't light for many seconds, and then it will flash 2-3 times, then it's dark for a long time.
Any ideas what I should check?
Thanks,
Mike
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