It’s very strange – only explanation I can think of is that the gong is only mounted on the crystal and not on the movement.
Yours are 180 degrees opposite my gong.
That means your hammer hits the “loose” end of the gong while mine hits the “steady” side.
With loose I mean the end further from the mounting point.
This should affect the sound?
Thank you, Claus for sharing!
Best
Blomman