Hi,
ifixit is not a parts supplier for Ninja products and does not any carry parts for a Ninja Blender.
If the blender is less than 12 months old, check what the manufacturer's warranty says about replacing defective components. Usually the manufacturer’s warranty statement can be found in the user guide that came with the blender.
You will have to contact Ninja’s customer service section as per the warranty guide, about getting any replacement parts, either under warranty or perhaps not as they may deny any warranty claim as they may say that the damage was caused by the user. You can only ask.