On my Tour Master there was also a wall switch near the table adjacent to the small desk (which I think was a feature on some but not all units...mine was a T40C.)
Since I had the wall switch for turning the circuit completely off, I replaced the on-fixture pushbutton with a toggle switch that allowed the three lamps to be either in parallel for full brightness or in series to simulate dimmed (candlelight) dining illumination levels. There is a thread on this site about that modification.
https://www.gsowners.com/forums/showthread.php?t=1859
This was when I was not skilled at posting images so Bob helped me out quite a lot at that time. I also did a similar modification to the bathroom 4 lamp fixture to achieve a night light level of brightness...
Chuck