Make sure the globe holders are lined up with the chair itself. Even try playing the game without the plastic chair mounted. See if the 555 lamps fall out. I did notice this problem once and it was because the chair plastic was brittle and had shrunk, forcing the globes out.

You may be onto something Nino i did notice that the lampholders were not centred in the chair hole openings maybe the chair has shrunk i will look tomorrow