DIAGNOSIS This is common and usually not a defect. The mechanism is stiff when new and can bind if the basket is inserted at a slight angle.
FIX Always align the basket perfectly straight with the unit. Push it in with steady, centered pressure directly towards the back, not angling up or down. To remove, pull straight out with a firm, even tug.
IF THAT DIDN'T WORK Check the rails inside the fryer and on the basket for any visible plastic burrs or debris from manufacturing. A gentle rub with a dry cloth along the rails can sometimes smooth the path.
HEADS UP Never force or rock the basket sideways to get it out. That can damage the locking mechanism. If it's truly stuck, unplug the unit, let it cool completely, and try again with perfect alignment.