If there are spots or irregular lines appearing on the LCD displays within the ClassVR headests, this is usually indicative of sun damage. The spots can vary in size and colour, but are usually a light colour such as yellow or white, or clusters of dead pixels.
The issue is caused by sunlight entering the headset through the lenses and being concentrated onto the internal LCD screen, heating up sections of the display until permanent damage is done.
This can be prevented by ensuring the devices are kept indoors and away from sources of strong sunlight such as windows or skylights, and that the headsets are stored in their case or trolley in a cool, dry and sheltered location.
You can also try rebooting the headset to see if any dead or stuck pixels reset, but if the same pattern continues to show, this indicates permanent damage.