White Line on Card

unfortunatly is sounds like a "print head" type of problem. By printhead I am refering to the assembly that causes the film to transfer to the card.

I would suggest creating a card project that has a full photo as the background.
This will show you if the streak runs the length of the card.

It could just be dirt or an obstruction in the card path. Try the alcohol cleaning cards.

Dissassembly of this printer is a crap shoot.

I have done it once. It is one of those things that is best left to someone good at printers or best by someone experienced on these.

if all else fails call a dealer like Datacard and ask about depot repair.