When printing normally any smoke generated under the print head is blown away vigorously by the fan in the print head. I believe this also serves the purpose of blowing out any flames that might start where the laser is hitting the surface.
I’ve noticed lately that doesn’t seem to be blowing any air sometimes. Sometimes the smoke almost leisurely wafts away from the cutting location. Today I had a rather large flame sprout while cutting some proof grade maple plywood. I almost popped the lid when the fan seemed to wake up and blew it out for me.
The main exhaust fans seem to be working fine, at least their noise is consistent with how it’s always been.
Can the print head fan be replaced? I feel perfectly capable of replacing it, it seems to be socketed electrically. Or do I need to get a replacement print head? These little fans have been a problem in every similar device I’ve ever owned. I’ve replaced the ones in my makerbot 2 or 3 times over the years so this doesn’t surprise me.