When I flush the toilet it just keeps filling and fillling! I can manually stop the flow of incoming water by pulling up on the floater, but I dont theink the floater is the problem. Im guessing its with the shut off valve because water shoots out of the top of the thing straight to the ceiling, and I dont think thats normal. (but I wouldnt know because this is the first time Ive ever looked at the insides of a toilet.) Please help! What do I need to replace? Can I do the repair myself or do I need to call a plumber?