All you have to do to solve this problem is clean your pullies after each use of sand and grit, and then apply a shot of reel magic. It is used by fishermen to protect gear and make fishing reels cast futher. This makes for a very smooth operation, and results in very little wear on the lines.
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Must exersise caution in changing to the stainless pulley models as they have sharp edges on them that may cause damage to the kite and lines. They are designed for a much larger diameter line than we use, and will cut through the line that they are connected to (not the line running thru the pully)