I lowered the action on my guitar and retuned it, then while playing I got the 16th fret and got a horrible buzz (totally not cool sound) from the A & D strings. Only on those strings and only at that fret. I tried adjusting bridges saddles in and out, the only thing that solves it is to move them back to a rather high action, which is exacty what I don't want.

Any suggestions? other than don't play notes on those strings at that fret.

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the vacuum store is a lot like the guitar store. but they do not attract the same clientele as the guitar store, cause if they did, the vacuum store would be loaded with a bunch of broke guys who just wanted to run the new vacuums.

Most likely your 17th fret or much less likely your 18th fret underneath those two strings is high. Yes, 17th or 18th fret.

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You dig?

Or wear on the 16th fret as well, you can do a quick check with a steel rule (straight edge) across several frets and see if it rocks or if there are tiny gaps.

If its a low fret you might recognize it from where you like to play.
This will need either a fret level or a single fret replacement to fix.

If its a high fret its a fret level, slot or fret repair or sometimes you can rubber mallet the fret back in (which can often just pop out).
In that case if a repairer thought it just needed to be knocked back in they will often clamp and super glue it.

Yes that is the acceptable fix for these problems super glue is the guitar wonder tool.