I thought I'd mention something that I found useful today. After several years of cleaning the chimney the usual way, with a 6inch nylon brush and brush rods pushed from below, I realized that the screen at the top is in no way being cleaned and cleared. Maybe the brush is now worn slightly, more so than when new, and that's the reason? I could always push the brush to the end and get most of it, but not this time. Oh what to do. The cap is 30ft off the ground, plugged almost solid, the brushes ain't cutting it, it's 7deg outside with a 30mph wind. I'm not going outside. So I thought a moment, and decided: drill a small hole in the end of one of the push rods, press in a piece of wire with a length just under the chimney diameter, run it up to the top and rattle it around a little. Nice and clear now, no climbing, and from now on I'll keep it as part of the standard cleaning. Maybe there is a better way, I'd love to hear about it. (The hardware store may have high tensile wire rod, small dia, something that won't bend into a pretzel like mild steel wire, but yet if if gets hung up, a slight pull and it's back down.)