I've just had a word with Paul Upton who was at my place when I was building that part and we both seem to think that it was something to do with the way part number BA21 (pulley) goes together. My memory is terrible but i'm sure if you examine those two parts very closely (VERY) there is a way of alligning them correctly. As I said before, I didn't have a clue why mine wasn't right until I took it all apart and inspected it ...... it's like a chinese puzzle LOL ....... let me know when you find it
