Oh man, I've been there - getting that dreaded 2 AM call with a cryptic 'Fault 87' and no manual in sight! Here's my go-to emergency protocol when time is critical:

1. First, I'd cycle the control power immediately. Many 'Fault 87' errors are related to emergency stop circuits, and a simple power cycle can clear transient faults.

2. Check the emergency stop circuit. 'Fault 87' often indicates an emergency stop input (ESTP) signal was triggered while the servomotor was energized. I'd trace the emergency stop wiring and check for any loose connections or faulty sensors.

3. Verify power supply to the servo drive. I'd check all incoming power connections and ensure proper voltage levels. Sometimes it's as simple as a tripped breaker or loose power cable.

4. Inspect all wiring connections, especially encoder cables. I'd look for any damaged cables, loose connectors, or signs of contamination from coolant or debris.

5. Check air pressure sensors if it's a turret or indexer system. Some systems use 'Fault 87' for air pressure problems in indexing mechanisms.

6. If all else fails, I'd try a parameter reset or reload known-good parameters from backup. Sometimes corrupted parameters can cause emergency stop faults.

The key is starting with the simplest solutions first - power cycling and checking emergency stop circuits. Most of the time, it's a sensor issue or loose connection rather than a major hardware failure. If I can't resolve it within an hour, I'd start preparing for a temporary bypass or manual operation to at least get partial production running before the morning crew arrives.