Hey there - I know exactly how stressful that 2 AM production line shutdown feels! When you're staring at a servo drive that's acting up but showing no error codes, it's like trying to solve a mystery in the dark. Here's my systematic approach that's saved me many times:

First, I'd start with the basics - check power supply quality (voltage fluctuations can cause intermittent issues), then inspect all wiring connections for looseness or damage. Even a slightly loose terminal can cause random motion loss.

Next, I'd monitor the drive's temperature - overheating without triggering alarms is common. Check cooling fans and ventilation. Then I'd look at the motor itself - test for bearing wear or mechanical binding by manually rotating the shaft.

The tricky part with no error codes is often encoder feedback issues. I'd verify encoder connections and power supply, then check if there's signal degradation in the feedback cables. Sometimes it's just a dirty encoder or worn encoder bearings causing intermittent position loss.

I'd also review the drive parameters - sometimes settings get corrupted or don't match the actual mechanical load. And don't forget to check for electrical noise or ground loops that might be interfering with signals.

The key is working systematically from external factors inward - power, connections, mechanical, then electronics. Document everything you check so you don't repeat steps. And if possible, swap components one at a time (like the motor or drive) to isolate the problem.

Hang in there - these intermittent issues are the toughest, but methodical troubleshooting usually reveals the culprit!