I am wondering the same thing. I just acquired a dtc100 with 40b last week, and no updates have been scheduled or completed. I have the 'white dashes' problem, and lousy synch with my lp350.
Also, does anyone know how to translate the '40b' version numbers into the 4.x.x numbers? In searching the 'net for firmware information for this unit, I see references to version numbers in both formats.