Look, these 300W halogen lamps did start fires, curtains etc. can end up on the top and cook.
They are only good when painting a room lol, you can see every crack and imperfection.
The triac dimmer inside the pole, some had a seperate module on the floor. I have one that uses a diode for bright/dim lol.
It's a PITA to take apart because unthreading the pole badly twists the wires inside.
I thought the on-off switch (adjustable dimmer) just turned off the triac?
It might be a WH148 w/switch on a PCB. The WH138 is too big.
Also, these are not PE grounded fixtures so the potentiometer/switch/knob has a safety function and plastic shaft too.