This is a new post replacing the other one since I messed up everything in the other thread while explaining the problem (I mixed things up). This post will be a lot cleaner for you guys who are helping, thank's in advance!
So, basically, the ball goes into the juggler and it works intermitently. When testing the metal contact underneath, sometime it works, sometime not. I would say it works one time out of 15-20. When it works, it could work 5-6 times than stop again (when putting the metal together).
I don't know where to start in the troubleshooting. Could it be the diode? the board itself. I saw in the manual that the juggler is J207-5 / J209-8. I took a multimeter to check J207-5 together with J209-8 and I have continuity, I don't know if it's normal or not. I also tested the solenoid via the test menu and it works. When I throw a ball in the juggler, it doesn't register anything in the switch test.
Thank's again for your help!