It's 2001. the allen key pivot bolt is fine, it's the 2 mounting bolts that attach the bracket to the frame and the slatted rubber mount that won't tighten. Ive packed it out now and it fits tightly.
Out of interest what bolts should I be checking for engine mounts, just to make sure im tightening all the right ones! Is it just the 4 at the front?
I'm going to be getting stainless downpipes soon, so hopefully that may solve the problem. I'm guessing its just the resonance of the old pipes thats causing it.