hi.

I user the allen screw which is being used in the flipper brackets. The black ones. They screw much tighter

Hi charsiufan

Please go to switch test (open coin door, push button and search for test>switch test)

Remove glass. Then empty balls from playfield, raise playfield a bit, pull it out (towards yourself) till you hear the click, then raise it upwards and lean against the back of the head of the machine.
Search for the drop target below the playfield and touch the switch below the target with your finger to test if you hear the 'beep' sound. (=switch test sound in switch test mode). If not, the switch is broken. Therefor the machine does not know that the door is down. The machine then performance a safety measure to ensure you always can reach the battlefield and keeps the door open at all times. You should replace the swith by soldering a new one on it. (take pictures!)

Hope this helps! And I'm sure someone else know things better than me
Peter

Great, thanks for the feedback! Enjoy the game, it's on my office and played daily by our employees! Fast and furious gameplay! Love it!