"Chorusy / tremolo-y" notes on G string.
 

Greetings, all. I picked up a Squier VM '77 Jazz here recently, and it's just fine for the most part, but I eventually began to notice that notes on the G string have a sort-of "chorusy" sound to them near the nut and progressively get more "tremolo-y" as I go higher on the neck, such that by the 12th fret, it sounds as though I'm running through a tremolo pedal with the speed set pretty high. FTR - I'm tuned in "D-standard" (whole neck down-tuned a full step) and the bass is intonated for this tuning. I don't notice this issue with any other string.

Any ideas what the problem could be? Thanks for your time and assistance.

Pickups too close to the strings? Try lowering them a bit at a time on the G string side.

You probably have a twisted string. Try loosening the string to release any twisting/tension. If the ball end rotates when you loosen the string, that's a good sign it was twisted. Re-tune and see if the chorus goes away or is at least reduced. The problem is that once a string is twisted and played for awhile, the string core can separate from the outer wrap making the chorus effect permanent. In that case the string needs to be replaced.

Once you fix the chorus problem check your pickup height as klaus suggested to avoid getting any pulsing effects in the upper register.

Great idea! Why didn't I think of that!

Great suggestions, folks - thanks! I'll give them a try and report back.