Only on the 1st copy, sometime on the 2nd, but not as many voids , and only when copying or printing in black. The void lines run from the top to the bottom of the page, not lead to trail edge. The spacers in the black dev assy aren't cracked. I've replaced the black drum assy because the coupler looked a little worn.
Any ideas?

Not saying this will be the problem, but don't overlook the primary transfer belt assembly in the mix. Could be losing bias potentially for the black transfer roller inside the belt.

Yup, shouda mentioned I have replaced the Transferbelt and Transfer Roller, as well the Black Drum. I replaced the coupling on the Black Drum Drive and am waiting to see if it is the solution.

The issue turned out to be Black Developer binding and the coupler jumping. Replaced the Dev unit and haven't had a reoccurance.

In my mind the highest likelihood is the black developing unit seizing.

But I've seen the exact same image quality issue when I applied conductive grease to the drum drive coupler. I guess it just does not conduct well enough. If you get a sticky drum drive coupler use a drop of light oil, never conductive grease. =^..^=