Loads of posts if you do a search. the bumper hight is adjustable but the drop is usually for a reason. My nearside bracket was rotten and couldn't support the weight of the bumper - hence the gap. My offside adjuster was seized and I sheared the bracket trying to move it. In the end I got 2 second hand brackets from Autolusso, took them to work and freed the adjusters and starte again. Pics on the end of my project post.