Diagnosis
The safety switch in the base is a weighted pendulum design. It's meant to be sensitive, but excessive vibration or an uneven floor can cause nuisance trips. It's rarely 'defective,' but it can be reacting to its environment.
How to Fix It
First, check your placement. 1) Move the heater to the most solid, level section of floor you have—avoid wooden floor joists or areas near foot traffic. A tile floor or a low-pile rug is best. 2) Make sure all four feet are firmly on the ground. Rock the unit gently; if it wobbles, the floor is uneven. You can place a thin, solid board (like a cutting board) underneath to create a stable platform.
If That Didn't Work
Inspect the base. With the unit unplugged, turn it over and look for obstructions. Sometimes a carpet fiber or debris can impede the swinging weight of the switch. Gently clean out the base compartment with a vacuum hose nozzle. Listen for the switch inside moving freely with a slight *click*.
Heads Up
Do not attempt to disable or tape down the tip-over switch. It's a critical fire safety feature. If the heater is constantly tripping on a seemingly level, solid floor, the switch mechanism might be damaged from a previous hard drop. In that case, contact the manufacturer—it's not a user-serviceable part.