First, let me start by thanking you for the time you spend reviewing stuff and flagging it. It's helpful and appreciated even if some of your flags do get declined. I'm pretty sure you have to make quite a prolific number of declined flags with no or very few approvals to get a flag ban, even if you did, I'm pretty sure it can be cleared (I've never seen someone get a flag ban on any of the sites I mod on, at least not that I'm aware of.)
In general though, not an answer should only be used if it isn't even remotely attempting to answer a question. Both of those are attempting to answer the question. The first answers it in the form of making suggestions to check after confirming how they think things should work. The second Rory already commented on. It's important to remember that we don't take a stance on correctness of answers. Someone could just about answer that there is noise on the audio interface because the alien space people are trying to take control of your mind and it would still not be NAA (though it might be patent nonsense if they don't otherwise have constructive posts). Moderators are specifically not supposed to judge the correctness of an answer. That's what the voting system is there for. However misguided an answer may be, if it is trying to answer, either directly or indirectly, it isn't really a fit for NAA.
With a weaker answer, the best bet is to comment on it instructing the well meaning contributor rather than flagging as NAA or VLQ (very low quality). The idea of the system is only to remove content that clearly doesn't belong and otherwise work on refining well meaning contributors in to great contributors.
NAA flags are really intended for things like asking another question or making no attempt to answer (treating it like a forum post rather than a Q/A site). No amount of editing should be able to salvage a post for it to be a valid NAA (not an answer) flag. If it can be edited to be an answer, then it is a quality issue, not a fundamental misuse of an answer.
VLQ are similarly for something of an extreme. In these cases, the post attempts, or appears to attempt to answer, but is bad to the point that it can't be meaningfully fixed. It isn't really for answers lacking sufficient detail or even link only answers so much as it is for answer that are illegible or incomprehensible. If it is clear they are attempting to answer, but it isn't possible to tell what they are trying to say, that's a really good VLQ candidate. Otherwise, commenting and/or downvoting is really the better way to deal with it.
On these, I'll normally be more forgiving and still mark something that is link only or minimal detail as helpful and just not take action (or just add a post notice), but I'll normally comment on the flag review notes that it wasn't really the right use. I'd be more strict on them, but with the size of the community, it can sometimes take a while for post notices and such to get placed due to fewer high rep users looking through content, so having a bit of flexibility on VLQ seems reasonable.
Also, if you check your flag history, I will generally use more descriptive comments on any flags I decline unless they are really obvious invalid uses of the flag (though I'd consider both of those answers to be pretty clearly not NAA and think I did decline the first without further comment.)