Quote:When it gets dirty. (How's that for another vague reply?)
How often really depends. Everyone has different levels of dust in the house that'll clog things up. I pulled mine on my RS56 after 100 hrs and there was absolutely nothing on it, not even a slight film of dust. So for me, it's not very often.
So I'd suggest keeping an eye on it and cleaning it as required.
The same way you'd clean your furnace filter - it'll vary like crazy from one person the next depending on living conditions, usage, pets, etc.
Edited by kal - 3/26/13 at 5:29am