If you open the fan up and inspect the motor, check if the motor has 2,3,or 4 wires coming off it. If there are only 2 wires (ie red & black) I would suggest a fan controller module that does pulse width modulation (PWM). Make sure it’s rated at least 12volt and minimum 4 amp. A product similar to this one https://www.amazon.com/dp/B078YSV8PJ/ref=sspa_dk_detail_2?psc=1
You may even be able to find a controller module with a reverse setting switch, a feature not available on the Fan-Tastic 1200 but is available on the 1250. I’m not sure on the internals of the fan you have but you may be able to completely replace their control module & knob with something similar to what I previously linked. See this guys video https://www.youtube.com/watch?v=nv90gyioT_8 (Warning there is a safety cringe moment in the video at @ 1:24 )
If you do this to your fan please make sure there is also an inline fuse (some modules have them built in) if the controller fails you don’t want to start a fire.