Review on 2-Pack Kohler-Compatible Canister Flush Valve Seal Replacements for Toilets - Equal to K-GP1059291 by Dustin Lannan

Fits perfectly and eliminates the "slow leaking" problem. Paper with instructions is included, but basically: 1) Turn off water in toilet and flush 2) Pull moldy fill tube out of center of canister stem 3) Lift tank out of place and slide under canister, grasp center stem and rotate counterclockwise about 45 degrees and pull the rod and canister straight up (you can twist the rod out all the way up if you want but I think it's more likely to break and then you're SOL) 4) Remove the old, stretched gasket and install a new one. (At first it looks like the new gasket is too small, but just gently slide it around and into the groove and it will snap into place.) Now take care of the other toilet as it will likely need a new gasket as well.