I have just bought a 1985 Ltd 440 belt, only 12,600 on the clock and virtually rust free. However, after 1 hour of riding at 60+mph, the belt starts to squeak & squeal like a Lada with a slack fanbelt. Book price is £206 for new belt and £260 for pulleys (ouch), but old un looks fine. Any ideas? I live in Yorkshire UK