I recently spent some time with an SG Modern Standard I was intending to purchase.
First thing I did was adjust the action. The factory action was slammed and not buzzy, but "pingy" and I like to strike chords hard, I like legato and bending and mostly lead work...alternate picking... I like to pick articulately and deliberately and the low action you can't even get under the strings for a bend. So I raised the action, strings somewhere around 3.5mm on low E at the 12th fret, and 3mm on high E.
Of course once you raise the action, one must raise the tailpiece so the strings clear the back of the bridge which was rather high because they all cleared well except for the high E. I opted to top wrap the strings. Long story short, I had the action feeling good, string tension was tight and felt good...i had some great tones dialed in and the notes and harmonics and pick-ups...she was dialed in and life was just about perfect. I love the neck, the body shape, cherry red, inlays...control layout and tone, feel and playability.
I went back for another session later and as I'm playing a little before I turn the amp on I felt the treble string B and E sound really tinny, metallic and loose although they were in tune. There was a noticeable difference in feel with the tension and bending and tone. Saddles all appeared in place, everything else was the same as when I was enjoying it earlier. I did some aggressive bending, like regular 2 fret bends so nothing crazy but I do like to bend and vibrato...can't help but think I upset something and really have no idea what because it's a pretty straightforward bridge design and not really a lot to mess with. It almost felt like the saddles dropped a fraction and lost their tension and mojo.
I thought I'd restring the guitar and so I did. I went back to regular restring, no top wrap and the looseness was even worse. Especially around the 5th fret high E where it felt could easily slip off the fretboard where as when I was playing before, I loved that the high E stayed on the board nicely and I was very fond of the neck and tension. Of course with high action, I had approximately 1cm of threads showing on the tailpiece which I'm sure didn't help with maintaining a tight feel so I think if I opt for this guitar I would have to stick with top wrapping.
Could this have something to do with that spring under the bridge?
Is it possible I upset the truss rod with a top wrap and after some playing it increase the forward bow and loosened everything up?