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Navigate to DIAGNOSIS > SERVO > (select axis) and monitor registers #0 (Position Deviation), #2 (Load Meter current %), and #6 (Motor Speed). Check if load meter consistently exceeds 60-70% during normal operation.

Manually move the affected axis with handwheel or incremental jog at low feedrate (F10-50) and feel for binding, excessive friction, or uneven resistance. Check coupling alignment, ballscrew bearing condition, and way lubrication.

Use JOG FEED OVERRIDE to limit torque during manual checks if mechanical damage is suspected.

Check Parameter 2041 (load inertia ratio) for the affected axis. Verify actual mechanical load hasn't increased due to tooling changes, fixtures, or worn components. Typical ratio should be under 30:1 for optimal performance.

Inspect coupling, ballscrew nut preload, and bearing condition. Verify proper lubrication on slideways and ballscrew. Disconnect motor from ballscrew and manually rotate to isolate motor vs mechanical issues.

Lockout machine power and follow LOTO procedures before disconnecting mechanical components.

Verify Parameter 1020 (serial spindle/servo motor number) matches the actual motor model on the axis. Cross-reference motor nameplate with Fanuc motor specification manual to confirm correct 4-digit motor code.

Check Parameter 2019 (continuous rated current) and Parameter 2020 (maximum current) against motor nameplate specifications. Verify Parameter 2135 (thermal time constant) is set correctly for the motor model (typically 10-30 for standard motors).

Access MAINTENANCE > PMC > SIGNAL and verify amplifier DIP switch settings match motor voltage and feedback type. For αi series, confirm software motor parameters downloaded correctly via Parameter 0020 bit settings.

If motor was recently replaced, execute SYSTEM > SERVO > SETTING and perform Auto Tuning Setup (Parameter 1815 set to 1 then cycle power) to optimize current loop and thermal monitoring for actual motor characteristics.

Auto-tuning will move the axis. Ensure safe clearances and reduce rapid override to 25% during first execution.

Verify motor cooling fan operation (if equipped). Check Parameter 3735 bit 1 (cooling fan control) and PMC signal SFAN (G0049.bit for axis motor fan) to confirm fan activation signal is present. Listen for fan operation during motor movement.

Measure cabinet ambient temperature near servo amplifier using IR thermometer. Check amplifier heat sink temperature (should not exceed 80°C). Verify cabinet cooling fans operational and intake/exhaust filters clean.

High cabinet temperature may indicate multiple thermal issues. Check amplifier LEDs for additional fault codes.

Review duty cycle in actual program. Navigate to DIAGNOSIS > SERVO and check register #2 (load meter) historical peak values. If continuous duty exceeds 70% rated, consider increasing cycle time, optimizing toolpaths, or adding dwell periods for thermal recovery.

If ambient conditions have changed, adjust Parameter 2136 (ambient temperature compensation) if available on your control series (30i/31i/32i). Consider adding external motor cooling fans or improving cabinet ventilation for sustained high-duty applications.