Have been using the Kohler easy close plastic toilet sear since we moved in, almost four years ago. recently the seat seemed to be loose but was held to the toilet tightly by the anchor bolts. Just yesterday I tried to lower the seat lid and it just dropped! I took the hinge apart using the instructions supplied by Kohler and discovered that the white pin was split on the end that goes into the actual seat and appeared to be getting soft, almost like it was melting. The other pin with the black tip was also getting soft and was leaving a greasy black residue. We only use “scrubbing Bubbles” spray cleaner to clean all our Kohler toilets and faucets. What could be the cause so we don’t continue having problems with the replacement.