The "whirlpool" action seems to work fine but all the water don't go out of the bowl. Could it be the little hole at the bottom of the bowl? What is that for? Plenty of water in the tank and it all empties out OK, just won't go all the way down. Can't afford a plumber so any help would be great. Also if I use a plunger while I flush it works fine... its like it just needs help getting started. Thanks