on this engine all 6 are along the top under the air induction ducts. even if one snapped it surely wouldn't be to difficult to drill down into it and use a nut or stud extractor bit to remove ? especially if its a garage with all the gear to hand. local garage is quoting me £100 to fit all 6 as long as none snap. ill start spraying release oil into them to soak in as it goes in on Monday.