Spoke with Chris Shinn in PE yeterday about replacing my doo,which he can do no prob,interesting is that he reckons that if the cam balancer(think thats its name) is adjusted every 1000 kms,the doo would far less likely fail(still recomends changing it)The amazing thing was how simple an operation this is-i went home to check it out,and it took me at least 5 mins! It is all in the manual--for those who actually read it.