Knob too short any suggestions?

Please post a photo of the part that does not fit. They might sell after market pieces that may work.

Try an appliance parts specialty store

What knob? Are you referring to the hole in the bottom left corner?

It's factory made to be recessed as a safety precaution. If you can pull the knob out and take it to Home Depot, Lowe's, or Menard's. They have a specialty section in the hardware/fastener section. Any knob will work. It all depends on how it mounts on the shaft. Some are C spring, half moon connector, or spline.

Who is the manufacturer? Did you buy it new or used? Is it a wall heater or wall fan? If you google "electric wall heater replacement knob" you will be able to find a lot of replacement knobs, but you need to know the manufacturer (Cadet, Broan etc). This looks like a Cadet wall heater to my eye. Best of luck.

Yes the knob is to short so it falls out.replacement won’t help because it would be same size none longer

You can buy kits which include extenders for the shaft that the knob fits over. The extenders (there are three included and each has a different shape to fit over the shaft on the inside that the knob fits over). They are not a longer knob, they extend the inner shaft so that it extends out farther, and then the knob fits over the extender.

Take the knob to a hardware store to see if you can find one similar but longer. A pot knob may work for you.