license plate bulbs

[cooks]

Hi, both my license plate bulbs have gone off and one of my rear lights. Just wonderign if there could be a reason for this? Like a fuse or if i jsut need new bulbs seem odd for both to go.

[cooks]

Also how do you change them?

[cooks]

After looking at them there seems to be quite abit of rust in the housing? Is this normal or could this be the problem? also one of my back lighst are out tested bulb in otehr light works fine any ideas?