Thank you for joining the Intel communities.
Unfortunately it is not replaceable, if at some point the unit fails you can request a warranty replacement if the unit is still under warranty, this unit has one year warranty.
You could try to replace the fan, if you can find the part but that will be under your own risk and the warranty will be void.
Thank you for the honest response. Yes, if it were in warranty I would go that route. Out of Warranty I would be on my own. I only asked because we are considering selling this unit to our clients as an RDS terminal in an environment prone to dust and fur. They expect PC to last 10 years and are shocked when they don't. Given that this unit is built as a throwaway device I did find a company that manufactures a bare wire replacement fan for the stick PC. I don't have the website handy. It would take some work trying to replace the 3 pin interface, but a savvy tech with steady hands could do it.