Are you sure Avalon wasn't talking about the enclosures? Maybe they didn't understand what you were asking.
Try a very soft horsehair paintbrush and lightly swish the dust away. You can also try a vacuum cleaner using the curtain attachment that has the long bristles on it. Another way is to simply use a can of compressed air for cleaning computer keyboards only keep the air movement back 6-8" while using a light sweeping motion...
Cleaners are a BIG NO-NO!!
To be serious also be sure to change furnace air filters once a month during constant use and 6-8 weeks during the spring or fall when you are not using forced air as much. I find a big difference when I let it go past that in my newer home. I also use the 3 pack-$7 NaturalAire filters from Home Depot that are wrapped and not the cheap blue ones that start collecting dust prior to getting used in your home. I agree with the soft bristle brush and simply take your time using no force against the driver.