Sorry to be a bit late to the thread Tess, I use a spanner like to one above, though a wee bit shorter. I do suggest though a pause for thought on replacing the fixed long dip tube with a floating one. I've 6 kegs and they all have long dip tubes and work really well. there's a small dimple below the dip tube and any slight debris that settles out will fill it. Sometimes the first pour is a bit murky if I didn't transfer properly clear beer but it clears quickly. The main use of a floating dip tube as far as I'm aware is if you are going to use a corny as a secondary fermenter so will have much more yeast debris, similar to the idea of cask conditioning.
Anna