Navigation tail lights are quite simple to work on. The forward bulbs are much less pleasant, but neither job is tough to accomplish.
These bulbs are 10VAC bulbs. There are transformers
in the wing tips that convert 115VAC down to to 10VAC. These transformers receive their power from two separate relays. Two lights forward, two lights aft, and two transformers on each wing tip. Two lights (one forward - one aft) are powered by one relay/transformer set. If one relay/transformer set fails, there will still be two bulbs illuminated.
I have changed plenty of relays, but not one transformer. The relays actually power a transformer in each wing. It's almost a given when doing a walk-around and seeing four bulbs out (one at each pair) that you've lost a relay or a breaker is popped. Airbus aircraft (at least the A300) use the same operational voltage.
Inboard socket pulled out. The strobe light has to be pulled out to remove a socket screw. Wires pretty dang short, but enough room to get to the screws.