When I flush the toilet it diesn't go down every time. What might be causing this?

It sounds like a clog either in the trap of the toilet or the main drain after the toilet. You could try a Closet Auger to see if it is in the trap. These can be rented. If this doesn't work, you may have to remove the toilet and run a Plumbers auger through the main line. You may want to try a Shop Drain Opener Chemicals at Hardware and Tools Corp. (http://www.hardwareandtools.com/icat/drainopenerchemicals) called Drain Care. It is an enzyme drain cleaner that clings to the clog and "eats" it, unlike caustic drain cleaners that just go by the clog and down the drain. Depending on what the clog is, it may take more than one application. Put it in at night and let it work. It's available at home centers, hardware stores, department stores and even some grocery stores.

I agree with biggsie 99.5% everything except the Drain Care. Can't pay him another complement for a while though. If you properly rod the clog you won't need the chemical and that's what I always shoot for. I am sure there are lots of great things out there from Dow and other companies but rodding is all you need.