You can try cleaning out the ravine or using oil ... but when that doesn't work then your going to have to remove the toilet and replace the defective mechanism. In hindsight some who have done this procedure might recommend replacing the toilet - there not that expensive and some of the newer toilets are much better than the old ones. In short - removing the toilet in some rigs is a PIA and if you have to go through the trouble why not replace it with something that is new?. Just my 02.