I think the moral of this story is that if you do choose to fit an additional countersunk/cheese head screw through the base is choose a screw bigger than you think you need.... (and make sure you have a good sharp drill bit for the stainless)
Alistair[/quote]
Hello Nick
I use two 6mm dia hex head screws about 50mm long. They have been there for about 10 years now, never shifted.

I fitted them on the underside to close the gap shown in your photo. I still have the original screws in the sides.