If there is an old question that has received no or inadequate answers, it is likely not going to get an answer without intervention, as it is not appearing high enough on the lists of new or unanswered questions to get the attention of people who may be capable of providing an answer. If someone wants to see a particular question answered, what are the different methods they can use to get it the attention it needs? Is there a way to bump questions up these lists? Are there different methods available for those who are the original poster vs those who aren't? Are there any rules of etiquette that should be adhered to as well?
This might sound strange, but just upvote the existing answers!
If the authors are still around this works remarkably well to trigger an update of outdated answers because many of the users will have a look at their post if they receive an upvote to an very old answer and sometimes within a couple of minutes they will update an outdated post.
Even if this does not work, it certainly is worth a try - you can't lose anything.