my nutri bullet pro 900 is leaking from the bottom of the cup when i blend, what's wrong?

Diagnosis

The leaking issue in the NutriBullet Pro 900 is almost always caused by a failure in the primary seal between the extractor blade assembly and the plastic blending cup. This leak typically manifests as a steady drip or a sudden spray of liquid emanating from the base of the cup during the high-RPM blending cycle. The root cause is usually a compromised Gasket (the black rubber O-ring), which has either become displaced, worn down through friction, or developed a microscopic tear. Because the Pro 900 operates at high speeds, the centrifugal force pushes liquid against the walls of the cup. If the rubber gasket is not seated perfectly flush within the groove of the blade assembly, or if it has stretched out over time, the seal fails under pressure. You can confirm this by filling the cup with water (without blending) and letting it sit for ten minutes; if water pools at the bottom, the gasket is the culprit. If it only leaks during blending, the seal is failing under the pressure of the motor's vibration and torque.

How to Fix It

To resolve the leak, you must inspect and reset the sealing mechanism. Follow these exact steps:

1. Unscrew the extractor blade assembly from the cup by turning it counter-clockwise.
2. Locate the black rubber sealing ring (the gasket) situated in the recessed groove on the underside of the blade unit.
3. Remove the ring entirely and inspect it for any nicks, cracks, or "flattening" of the rubber. If the ring feels loose or looks translucent/worn, it must be replaced.
4. Clean the groove of the blade assembly using a damp cloth to remove any dried food residue or sugar crystals, as these create gaps that allow liquid to bypass the seal.
5. Press the gasket firmly into the groove, ensuring it is centered and not twisted. Use your fingernail to push the ring evenly all the way around the circumference of the blade assembly.
6. Thread the blade assembly back onto the cup. Tighten it firmly by hand, but do not over-torque it with tools, as this can warp the plastic threads and actually create a leak path.
7. Perform a "dry run" with water to verify the seal before adding ingredients.

If That Didn't Work

• Inspect the Cup Wall for Hairline Cracks: Examine the plastic of the cup specifically near the rim where the blade assembly screws on. If there is a stress fracture or a chip in the plastic threading, the gasket cannot create a vacuum seal. In this case, the entire cup must be replaced, as plastic fractures cannot be safely glued for food-grade high-pressure use.
• Check for Overfilling: Ensure you are not filling the cup past the "MAX" line. When the cup is overfilled, the liquid is forced upward into the blade assembly's internal housing during the vortex phase, which can push liquid past the seal and down the sides of the motor base.
• Verify Blade Bearing Integrity: If the blade assembly feels "wobbly" or doesn't spin smoothly, the internal bearings may be failing. A wobbling blade causes the entire assembly to vibrate excessively, which momentarily breaks the seal of the gasket during operation. Replace the entire blade assembly unit if the shaft has any side-to-side play.
• Clean the Base Connection: Ensure the motor base is level and the cup is locked fully into the twisting mechanism. If the cup is tilted even slightly, the pressure distribution on the gasket is uneven, leading to leaks on one side.

Heads Up

• Never put the blade assembly or the rubber gasket in the dishwasher; the high heat can warp the rubber and cause it to lose its elasticity, leading to immediate leaks.
• Avoid using the NutriBullet Pro 900 for liquids hotter than 160°F (70°C), as extreme heat can soften the gasket and cause it to slip out of its groove during blending.
• Periodically inspect the gasket every 30 days of regular use. If you see any "stretching" or thinning of the rubber, replace it proactively to avoid damaging the motor base with leaking fluids.
• Always ensure the blade is screwed on straight; if you feel resistance during threading, back it off and start over to avoid cross-threading the plastic.