Trouble with cross-Atlantic terminology! The items I described as 'cam followers' are certainly what you describe as 'HLC's' and all 16 were changed along with all the rockers. The reason for the repair was to cure a 'ticking' noise when warm that my mechanic had diagnosed as a worn cam follower / HLC. Once rebuilt, the engine has not just a 'tick' but a good solid noise just like a diesel when cold but is totally silent now when warm. I showed the mechanic the reply from ILUVMILS and he admitted that he hadn't known to check the 'basic position' so I hope this will turn out to be the solution but if so I'm a little confused as to why the noise disappears when the engine warms up? It does behave just as though oil is draining out of one or more HLC's - would the oil be more likely to drain if the preload was wrong? I'll certainly try and find your post on checking the HLC's.