Falcon 2 40w laser module build up on the cooling fans

I have a Falcon 2 40w machine that is two weeks old, and while i was cleaning the module i have noticed a buildup of black substance stuck on the cooling fans, i guess this is from the wood i have been using. Can this be cleaned off safely and what would you clean them with? I use window cleaner for the slats and base that works very well.
Thank you in advance.
Ray

If the internal part of the module does not get soaked yes, just clean it. I usually use isopropanol mixed with distilled water.