Carefully measure the diameter of the cylinder chambers then purchase a reamer of that size. Clamp the reamer in a small T handle. Get everything well lubed with dark thread cutting oil, then *slowly* turn the reamer down into the cylinder chambers by hand until you feel it touch the step in the cylinder. Then slowly turn it as you bring it back out.
If you use a reamer that's the same original size as the cylinder chambers it will only touch and clear out the high spots in each chamber.
