I clean mine about twice a year. I took it down off the shelf a couple of days ago because it was running very sluggish. When I turned it around to the side I couldn't see the vent holes were totally clogged with fabric lint and dust, I'm surprised it didn't catch on fire...and they have been known to! I know someone that had a house fire because of it. I took the side cover off and took it out to the shop and blew the inside out with the compressor. It was loaded with dust and lint. The fans were hardly turning. If your computer is in the same room with your fabric you need to clean it more often. We don't realize how much fabric lint there is.