also try wigging the lamps in the socket. Most common issue for dim lights is the sockets.

if wiggling makes the lamp bright and it feels loose in the socket, you can sometimes with lamp power off "hook" the center tab that contacts the lamp tip and bend it up to apply more pressure to the lamp. I often use a small allen wrench to get under the tab and pull it up.

if the socket is oxidized badly, it's probably easier to just replace it if a quick cleanup with wire-wheel-on-dremel doesn't fix it.