Just got around to blowing these up.

Looks like you have Thrips.;

Attachment 292070
The small scooped out spots in white outline are the damage.
The red outlined are the culprits.
I'll bet that you find tiny black dot on the undersides of the fans.

Here's a good place to start;
Thrips: Identification, Control and Prevention of Thrips

Aloha and good luck,
Weezard