Look at where your feeder is placed. Be sure it's not vulnerable to predators. At the same time, make sure it is not in an open area, away from the cover in which birds usually travel. Birds don't have sweat glands in their feet, so they won't freeze onto metal feeders. There's no need to cover any metal feeders parts with plastic or wood to protect birds' feet, tongues or eyes.
Birds have no teeth to grind their food.
The dirt, sand, pebbles and grit they eat sit in their crop and help grind up their food. Adding grit to your feeder is helpful, particularly in the winter and spring. There is no evidence that birds can choke on peanut butter. However, birds have no salivary glands. You can make it easier on them by mixing peanut butter with lard, cornmeal or grit.