I asked the same question to Phile bailey. Based on the manufactuer and the year of the car and all the appearence, he said he's "almost certain that I need a new starter". So I'll change it. almost 10years, it's about time anyway.
It seems the humid weahther is the biggest problem. Whenever it rains, my car has problem to start.
Yesterday, it happens every time when I start the car. Every time there is just a 'click' from some where. But there is one time the start begins to roll but after 2 2nds it stopped, like no battery. Keep trying several times, it starts.
Thanks for Don Cherry and harbin man for providing your expert advices.