Why is Motion3 degrading my non-compressed exported clips?

Going nuts here -- coming into the home stretch of a very long old movie/vidoe restoration project in Motion 3, and even though I've been exporting my cleanup work into solid clips with "none" as my compressor, the image qulity is degrading -- type and video that was clean and sharp is blurred! I thought I had the mystery solved when i stopped working in 16 bit color space for my 8 bit capture (thought the larger color space would give me better levels tweaking, but it didn't -- made images look blurred), but now that i'm down to the wire and wanting to export ( "none" compression again) a last time to work with audio and chapter markers, all of a sudden (so it seems) my images are blurring! this is making me crazy.

I thought working with no compression -- not even "animation" -- had solved my problem with successive image degradation that lots of image stabilization, replacement and cleanup was bringing when using animation, apple intermediate codec, even prores compressors; "none" for compression literally cleared the problem up. Now seems it's all going down the crapper as i come to an end of my work. Even after constant trashing of Motion's prefs for all I've been pushing it to do this.

Anybody else have this problem ever, or am i or my project (or both) hopelessly snakebit? Also, have no choice but to use Motion 3, of FCS2, cuz I'm working on a Dual 2 G5 PPC -- no moneys to upgrade.

thanks