I have 3 Kolher Champlains (K-3390-EBA) in my house and all three now require me to hold down the handle for a long time in order to flush. Also one of the three is very slow to fill the tank. It takes about 10 minutes. I have the parts diagram from Kohler, but since I am not a toilet expert I have no clue which parts to replace to fix these issues. Any help would be appreciated.