Wanted: Replacement Hayes MX2 mechanism

The locking grub-screw of the rear disc brake mechanism of my ATB has
rounded off, and won't allow me to adjust the static disc in or out.
I can
1. try drilling out the screw and re-threading
2. get a new mechanism.

I'm trying option 1 at the moment, which is proving difficult due to
the hardness of the steel of the screw. So I wonder if anyone has a
source of a spare MX2 mechanism.