dankomal.......... I'll ask you once again. What's that all about? How is putting glue/gunk under the 7th fret marker suppose stop a rattle? The 7th fret marker on a vintage neck covers only one thing ........... the hole drilled to accept the fret marker.
Did he remove the marker and drill a hole down to the truss rod? As you can see, there's a lot of wood between the 7th fret marker and the truss rod on a vintage style neck.
Compare that to a neck with the Bi-Flex truss rod that has a screw under the 7th fret marker.
Sounds to me like your guy doesn't know the difference. If you want it fixed, send it to
mellecaster.