ego mower blade stops spinning when i hit tall grass, but the motor is still running.

The blade bolt has loosened or the blade adapter is stripped.

1. Stop immediately. Disconnect the battery.
2. Check the prevailing torque hexagon lock nut (part number 5630351002) and washer (part number 5650705002). Tighten to specification.
3. Inspect the blade (part number 3707494002) and the motor shaft for stripped splines.

If that didn't work, the overload protection in the DC motor (part number 2730252001) is engaging due to excessive load. The mower is under-powered for the grass height.

Heads up: This is a safety feature, not a defect. Raise the cutting height using the height adjusting lever (part number 3322429001). Mow in two passes for very tall grass. Never remove or modify the overload protection.