The plunger of the 1B1X Ballcock replacement Kit made by Lasco for
Kohler is one millimeter shorter than the original Kohler plunger. This
fact requires that the fill level screw on the top center of the
ballcock to be screwed in all the way to compensate, causing the new
Lasco kit to have a shorter life. One option may be to switch the
rubber parts from the new plunger to the old one and continue to use
the old plunger with the new rubber parts. This is difficult since it
has to be done without damaging them. Another option may be to replace
the fill screw with a longer one. If the second option is used make
sure the threads on the ballcock cap are not stripped causing the
ballcock to continuously fill and even overflow and flood. To prevent a
possible overflow reduce the amount of water supply to the ballcock
enough so that the overflow tube over the flapper can compensate; this
should be done no matter what kind of toilet you have.