I recently had a misfire on cyclinder 2 on my Astra. Put it into the garage and they diagnosed a sticking valve. They did all the checks including a compression test which showed that it was down on cyclinder 2. They replaced the oil and did a engine flush, also added additives to petrol. However, it is still misfiring and now I am being told it will need the head taking off. Has anyone experience this problem and any solutions? Thanks