Mr. Sherlock, thank you for the kind help. You are so knowledgeable and so generous to share your knowledge with me and others. And thanks for the concern from KoNickon, Gumby and David. I hesitated to send the camera out because I haven't found a repairman familiar with this kind of camera and close to my place. New Zealand or USA looks too far away.
I was lucky that the shutter didn't give me much trouble. I opened the cover, then cocked and released it for some times, and found it seem work normally. I didn't find the reason of the malfunction. Maybe the shutter release mechanism is the culprit, as Mr. Sherlock mentioned for the third possibility. And the shutter release lever was easy to drop after the shutter cover was opened, and I somehow put it back.
But, the film wind lever stuck after several times of winding. I removed the top cover and found a small piece of metal scrap in the gears. After the wind lever was reassembled, the frame counter totally doesn't function. I guess I have damaged the frame counter spring, and the little metal scrap is just a portion of it.
Ok, the camera looks "working" now, except the frame counter. I feel both happy and sorry. A roll of film is in the camera. I wish the result could still be fine, and somebody else in the future could get lessons from my experience.