Scratched Flush Valves
I always think it's a crying shame whenever I see a top-quality, highly polished plumbing fixture like Royal®, Flushometer® or Sloan® Valve with notches and grooves crushed into it because some stooge used a common pipe wrench to work on it.
To protect the polished brass, gold or chrome finish on automatic flush valves, never use tooth-grip pipe wrenches when installing or servicing these valves.
Your best bet is to use a strap-wrench or a smooth-jawed wrench to tighten the couplings.
All sorts of wrenches are available that are made especially for work on automatic valves. These wrenches won't damage the polished surfaces.
Be professional. Buy the right tools for the job and use them.