tyming of vacuum into transfer drum

Please can anyone help me -- my press is old 4colors press. Before the vacuum pump is not working. I cleaned all the pipi and the sunction. Its' all now ok. The vacuum now is all ok. But my problem is that it is not in the exact timing when the vacuum is turning on. It will start vacuum when it is near into transfer gripper. I think it must start vacuuming the paper when the position is in the right side of the drum so it can hold the paper when I set into perfecting setting. The problem is that it will start vacuum the paper when it is near into transfer gripper. So it will not able to hold the paper so it will fall down. How can I adjust the timing of the vacuum into drum? Can anyone help? thank you in advance

 

You may be able to help people further by giving details of the actual machine which you have the issue on.

 

Hello guys did anyone help with this error? I already changed the board in motor but the same problem. Is there another possible problem with this error. MAIN DELIVERY PILE IS FULL