I just bought a VB from ebay. However, there seems to be a problem with one of the oscillating mirrors. When I close oen eye the image looks perfect, but when I close the other eye the image seems to swing from left to right, disappeating completely at times. Does anyone have any advice on fixing this? I would rather just solve the problem myself that deal with the person I bought it from as I would like to use the VB for a science project and wish to avoid all the shipping delays.