Ralf covered this in a relatively recent live mapping session here.

Welcome to the forum bakrin :)

Its starting to look quite a lot better.

I usually use at least 20% antialiasing, preferably 33% and sometimes higher.

Each of those bands is a pass made by the rendering engine.

You can use wider passes by typing the command EXPORTSETMPPP and hitting return. The command line will tell you the current Maximum Pixels Per Pass, which at default setting is 4000000 (4 million without commas).

Try typing 40000000 (40 million), hitting return, and trying your export again.

Try hiding the STRUCTURES(COLORS) layer.

That sounds like a really complicated operation.

What about consolidating all those tiny bits and pieces into larger png images in GIMP or some other bitmap app, and then importing the fully formed symbols as single entities?

Anyway...

If you want just one image to have a different origin import them all with the origin that is right for the majority, and then edit the one that needs a different origin from the Symbol Manager. Use View->Move origin to pick the new origin position while you are editing the symbol in the edit window.

Alternatively, you could just move that one symbol into a subfolder within the main one and import it on it's own with a different import origin.