Hi all, I am having problem with spin coater. At first there were some photoresist going into the chuck all the way to the bottom so the program stopped automatically after a couple of seconds of running. Also the platform was very hard to rotate by hand. After I cleaned the pathway which has the photoresist, the platform moves freely but the vaccum is showing insufficient value. Is there something blocking the vacuum somewhere? How could I possibly check the block? Thank you very much! Jia