Mrmerlin

FWIW dont use a ball end to loosen any allen bolt. Especially on the water bridge of a 928
one of three things will happen.
1 the bolt will come loose and the head will be damaged
2 the allen tool will slip in the head and damage the bolt possibly stripping it out.
3 the ball end will snap off into the bolt head giving a new set of problems

merchauser

I had success using an appropriate torx bit, but the bolt was no longer usable. I also replaced a few of the factory
bolts with grade 10.9 from ace hardware. I know a few have commented that they prefer the OEM bolts, but the harder
bolts made it a heck of a lot easier to remove on other occasions.