DIAGNOSIS This is almost always caused by food debris or grease buildup on the basket rails and/or the corresponding grooves inside the unit. The coating on the rails is not non-stick.
FIX Clean all contact surfaces thoroughly. 1. Remove both baskets. 2. Use a damp cloth and mild detergent to scrub the four silver rails on each basket. 3. Inside the unit, clean the four matching grooves where the rails slide (two per basket chamber). A soft-bristle brush helps. 4. Dry all surfaces completely. 5. Apply a *tiny* amount of cooking oil (like canola) to a paper towel and wipe it onto the basket rails. This acts as a lubricant.
IF THAT DIDN'T WORK Inspect the rails for physical damage. If they are bent or warped from impact, the basket will not slide properly. You must contact Ninja for a replacement basket.
HEADS UP Never force a basket. Misalignment can permanently damage the grooves. Always ensure the basket is level when inserting.