I have found a longer term solution to this now. Even using oven cleaner after dismantling was not entirely satisfactory as the VNT mechanism is not very accessible, leaving a slightly 'notchy' feel to the mechanism. So I bought a heated ultrasonic cleaner; water and a handful of washing soda and it's as good as new. Not the whole turbo, just the exhaust end with the VNT mechanism! Don't waste your time with Innotec.