Clean all ring grooves thoroughly with a squared-off broken ring or ring groove cleaner with a blade to fit the piston grooves.
The top and 2nd ring grooves are 1.2 mm (0.05 in.) wide. The oil ring groove is 2.0 mm (0.08 in.) wide.
File down a blade if necessary.
Do not use a wire brush to clean the ring grooves, or cut the ring grooves deeper with the cleaning tools.
NOTE: If the piston is to be separated from the connecting rod, do not install the new rings yet.