Magnavox Projection TV model PTV377-AH01 has a dark blue looking mushroom image located in the middle of the screen. Can this be removed?
Check the crt coolant chambers for evidence of bacterial growth. The fluid should be clear not clouded [with many particles floating]. If the fluid is cloudy then it should be replaced and the physical faces of the crts cleaned throughly. The other probability is the crts are old enough to become solarized.