Possibly similar model, but not exactly that model, at the link below:
https://www.manualslib.com/brand/brookstone/
MIght also find it included one sold through the internet, perhaps on ebay.com or amazon.com
Sounds like the control is damaged. You could try calling Brookstone service and see what they say (they have a one-year warranty). Number is 1-800-292-9819.
Sounds like the power is arcing, Probably broken porcelain insulators. I wouldn't recommend trying to use it, there is some really high voltage in there. Replace it or send it out for repair.
Question edited for clarity and toss in some CAPS.
Question moved from Televisions category.
Contact their Support for a warranty repair.
https://www.envion.com/en/ta750
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Question edited for clarity, dreadful spelling and typos. :>D
Question moved from Televisions to Air Purifiers.
Your air filter is dirty and needs cleaning.