1990 Toyota Camry Cartridge Bulb

For months now I have been trying to find out why my cartridge light bulb will work and not work in my dome light. When I take off the protector I do not see any breakage or rust corrosion. I take the casing out of the roof and the power connector does not look like it is damaged either. I am not really good with electrical checks and I dont want to blow my meters up so, I am asking you if you could tell me how to do an electrical check, or if you could tell me what the problem with my dome light is?