The Ninja Creami is a countertop frozen dessert system that puts high torque loads on the blade/paddle drive, especially with dense bases or under-processed "pints." A stripping drive shaft often happens when the mix is too hard, the unit is forced through resistance, or the assembly is mis-seated, causing the coupling and gearbox to wear. Repair can be worthwhile if the motor is healthy and you can replace the drive components or paddle at a reasonable cost.
Replacement becomes more attractive when the gearbox is damaged, the motor stalls repeatedly, or the interlock/safety switches fail-those can add labor and parts quickly. Owner behavior strongly influences longevity: letting pints temper slightly, following recommended fill lines, and keeping the drive interface clean reduces abnormal torque and can prevent repeated shaft wear.
If the unit is older and you've had multiple drive failures, replacement is usually the more reliable path.