To check if you have a clogged jet problem flush the toilet then pay close attention to the stream of water coming from the jets. They should shoot lots of water out diagonally around the bowl. If the water goes straight down that is a good sign that the jets are partially blocked. But by what?
That question is easy to answer with the help of a small mirror. Place the mirror under the rim and look at the jet holes. If you see dark orange or black spots then you have a bacteria problem. If what you see looks scaly and light in color mineral deposits are your problem.