Canned Yam with spare wire

[goodglarp]

I just purchased a completed Canned Yam bass preamp off ebay, and it showed up with a dangling ground wire. In the photo, it is the black wire just kind of laying against the output jack on the right, near the yellow signal wire.
It looks like it should be soldered to the ground tab of the output jack (which has no solder on it), but the seller says that doing so will cause ground loops and hum. I'd rather have a working pedal instead of sending it back to the seller as DOA for a loose wire. Suggestions?

[Soup39]

Take a look at the tutorial section here, I believe it confirms it should be attached.  Have you attached the black wire on the out jack to see if it does introduce hum and noise as the seller stated?

[kgull]

It shouldn't need to be connected as it looks like it's grounded through the enclosure. Put a bit of tape over the exposed end so nothing shorts out and see if it works. I wouldn't dyke it out or solder it just yet in case you are accused of messing it up if it doesn't work.

SUPER unprofessional to just leave a wire exposed and dangling like that but it shouldn't affect anything.

[goodglarp]

Ohmmeter confirms chassis ground continuity. Taped the loose end and tested: no hum.
That said, this unit actually attenuates the signal until the Level knob is nearly full clockwise, and the Q and Frequency adjustments do next to nothing. I don't feel like troubleshooting someone else's build, so it's going back to the seller.
Thanks for the responses.