I just read a reivew of a similar lens
http://www.bythom.com/18200lens.htm and I know why it's a bit stiff and rough while zooming
"The zoom ring is stiff and has a very different feel at different focal lengths (I should note that some users claim it is loose and subject to zoom creep; that isn't the case on my sample). As you zoom in to 200mm, the zoom ring has a sudden "loose point" just before you get to the maximum focal length. Zooming the other direction is smoother, though still what I'd call rough."
I guess having a fairly stiff zoom ring handling is a good thing to prevent zoom creep when shooting photos upwards or downwards.
However, when I zoom in or out of the lense still creates a very tiny dry screeching noise. Anyone else have a similar issue their lenses while zooming?