Toilets flush properly when the water from the tank flows freely into the bowl and when that same water can then easily exit the bowl into the sewer. If the flow at either of these locations is somehow reduced the condition you are experiencing will result. Unfortunately, it isn’t really easy to find a clog in the bowl. Sometimes a submerged mirror will reveal a child’s tow or some other obstruction, but most often it is necessary to use a toilet snake (a short version of the big plumber’s kind). A minor clog in the toilet trap can easily be removed with a snake. The other possible cause for the weak flushing action involves the water holes under the rim of the toilet bowl. Over time, these holes can become clogged up with calcium, again restricting flow – in this case – from the tank to the bowl. Removing the lime deposits that build up around each of these ports can reduce the flow enough to ruin the flush. Chances are you have either one problem or the other – not both.