I had a bit of a surprise on Sunday. I looked out of the window and realised that my turbine wasn't as high in the air as it was the day before, and that the blades were almost brushing a tree!
It turned out that the U-Bolts which clamp my scaffolding pole to the wooden part of my tower had expanded in the heat,(+ the wood had shrunk?) and the pole had drop vertically about 4 feet. I've tighten the whole thing up and put a pin in place as a stop.