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Navigate to SYSTEM > PARAM and record parameters 1815 (CMR), 1825 (position gain), 1826 (velocity loop gain 1st), 1827 (velocity loop gain 2nd) for the affected axis. Compare against OEM machine specifications or factory default values.

Check DIAGNOSIS > SERVO > screen 300-399 to view current position error (diagnosis 300) and servo load meter (diagnosis 436) for the affected axis during alarm condition or immediately after reset.

If CMR (parameter 1815) bit settings are incorrect for motor type (serial or pulse-coder), verify bit 1 (MCS), bit 2 (RSV), and bit 7 (RVS) match amplifier and motor specifications. Incorrect CMR can cause feedback polarity issues.

Changing parameter 1815 CMR requires power cycle and can cause unexpected axis motion. Ensure axis is clear before testing.

Reduce position loop gain (parameter 1825) to 50% of current value temporarily to test if alarm clears. If successful, gradually increase gain while monitoring position error until optimal tuning is achieved without alarm recurrence.

Place machine in EMERGENCY STOP and manually check axis movement. Attempt to hand-rotate motor shaft or manually move axis slide (with brake released if applicable) to detect binding, unusual resistance, or grinding sensations.

Disable amplifier or disconnect motor power before manually moving axes to prevent injury from unexpected servo activation.

Check servo load meter at DIAGNOSIS > SERVO screen 436 for the affected axis. Values consistently above 80% during normal motion indicate excessive mechanical load or undersized motor for application.

Inspect mechanical components: ballscrew coupling for damage, way covers for debris interference, lubrication system operation, and bearing condition. Check for crash damage to axis travel components.

If binding is intermittent, use DIAGNOSIS > SERVO screen 310 (disturbance torque) to monitor torque fluctuations during slow manual jogging to identify position-specific mechanical issues.

Check amplifier LED status codes on the servo amplifier for the affected axis. Solid red or flashing codes indicate amplifier-detected faults. Cross-reference LED patterns with amplifier series documentation (Alpha-i, Beta-i, or Alpha/Beta series).

Navigate to DIAGNOSIS > SERVO screen 400-409 to verify encoder feedback is updating correctly. Monitor pulse coder position values while manually rotating motor shaft to confirm proper feedback operation and correct direction.

Inspect encoder cable connections at motor and amplifier for damage, contamination, or loose connections. Check cable shield grounding and routing away from high-voltage AC power lines that can cause noise interference.

Perform encoder cable continuity test using FANUC cable test procedure or swap encoder cable with known good axis if identical motor series. If alarm follows cable, replace cable. If alarm stays with axis, suspect motor encoder or amplifier failure.

Disconnect encoder cable from amplifier before performing continuity tests to prevent amplifier damage from test equipment voltage.