Hello, I am very much a newbie to pinball restoration and I'm looking for some help and advice please. I have a Nordamatic Champion EM pinball (1975- All the parts are Gottlieb),which I have now got working. However, when the ball drops into either of what I call a pocket (there are two of them one next to each other, see photo), it normally gets ejected after a short period. This happens most of the time but every now and again it doesn't get ejected. I have checked the contacts underneath the pocket and they are clean and making and breaking correctly. Unfortunately I do not have the schematic for this pinball. Look forward to any suggestions as to what the issue may possibly be? Regards. Peter.