I am the original owner of a 3 year old RR WOZ. Recently it has developed a problem with the castle doors. I can knock a ball into the VUK after hitting the doors 3 times but the right door only partially opens. When the ball hits the right door it pushes it fully open. The doors close but when the doors reopen, again only the left door opens fully leaving the ball stuck in the VUK because it can't get past the right door. This eventually causes the game to search for the ball. How do I fix this problem. Do I need to remove the upper playfield to fix this? Thanks for your help/advice!