Did they pop in? Did they all seat the same? I used a very thin coat of Syl-Glide (silicon gel) and the holders slipped right in and they felt like they seated. If your seals were dry perhaps they didn't seat and the O ring is pinched between the holder and the head. But I am not a professional so be advised...

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Steve
1985 Mercedes 500SL Euro (Gray market)
1995 BMW 520i Euro (Gray market)
1992 BMW 525it Wagon
1994 Honda Del Sol Si