Can you modify the fitting so that it doesn't contact the deck at all anymore? Seems odd that the clearance is that tight for such a fitting.. As a deck stepped mast there really shouldn't be anything other than the mast tube contacting the deck area.
Photos would help...
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"