Okidata 3410 pacemark not printing correctly

Well, I had that problem once. What I did was that I used the printers cleaning tools. You can acces them by entering Printers in the ControlPanel. Then right click on your printer and select Settings. Look through there. Worked for me.

Get your screwdriver and remove the new printhead. Now, reinsert the printhead contact board in the slot firmly, and MAINTAIN FIRM FORWARD PRESSURE ON THE ENTIRE PRINTHEAD ASSEMBLY WHILE YOU TIGHTEN THE SCREWS. Not too tight, but very firm pressure FORWARD. I don't know why, but this almost always works to get you same gap as before you changed printheads.

It would be my guess that his answer did not help one bit did it? It sounds like an adjustment is needed here.   Unlike, most other Okidata printers the sdjustment is made not with the printhead but with the carraige rail that the printhead rides on.  This is made by loosening the screw to the at each end of the rail in tyhe black plastic piece thatslides through the side wall. then turning the plastic piece in either direction slightly and tightening the screw again.  You might need to do this a few times to get it right.