26-01-16, 12:55 AM
Most likely it is the seal seats a bit corroded, no need to polish the pistons just clean them well back to their shiney surfaces. If there are corrosion marks more than 5mm back they will probably need replacing.
Remove the corrosion carefully as you don't want to make the slots bigger. I usually use very stiff plastic cut to fit the seal slots and brake cleaner or maybe brake fluid to soften the corrosion.
Remove the corrosion carefully as you don't want to make the slots bigger. I usually use very stiff plastic cut to fit the seal slots and brake cleaner or maybe brake fluid to soften the corrosion.