I have recently acquired an Electrohome 3100 projector. Yesterday, the unit was working fine. Today, however, the bottom of the projected image is distorted. The cause of the distortion seems to be some sort of a bubble(?) inside the tube(?). When I shake the projector gently, I can see the bubble inside move, and this of course also makes the distortion of the image move. Does anyone know what is causing this and how (if) it can be fixed?? Where did this bubble come from???? Thanks!!!