I am not sure what type of bulb/receptacle you have as you did not include a model number.
If it is a standard incandescent bulb then try the following.
Unplug the unit.
Remove the bulb.
Look into the receptacle and you will see the center connector for the bulb.
Bend that up a bit.
Be gentle as they can snap off easily also be sure that you do not bend it over to the side.
Also check that the connector is clean.