Oh man, I've been there! Staring at that cryptic 'Fault 73' at 2 AM with production breathing down your neck is the stuff of nightmares. Here's my systematic approach that goes way beyond just power cycling:

1. First, breathe and document - Grab the manual (digital or paper) and note the exact fault code, any accompanying status lights, and what was happening when it faulted.

2. Check the basics - Power supply voltage (both incoming and DC bus), connections (tighten everything), and cooling (fans running, vents clear).

3. Decode Fault 73 - This varies by manufacturer, but often relates to communication issues, encoder memory errors, or gear engagement problems. For example, in some drives it's a communication loss fault, while in others it's an encoder memory error.

4. Communication check - Verify network cables, connectors, and settings. Check for matching transfer rates, proper addressing, and ethernet settings if networked.

5. Encoder/cable inspection - Check encoder cables for damage, ensure they're separated from power cables, verify shielding is intact, and test continuity if possible.

6. Parameter review - Look at communication loss handling parameters. Some drives have fault tolerance settings that might need adjustment for temporary disruptions.

7. Swap test - If you have a known working drive, try it on the same port/cable to isolate whether it's the drive or the infrastructure.

8. Clear and retry - After addressing any found issues, clear the fault and attempt a controlled restart with reduced parameters if possible.

The key is moving from 'what's broken' to 'why it broke' - communication issues often point to interference, loose connections, or parameter mismatches. Got coffee? You'll need it!