"Turns out that last year's coupler problems had the same root cause. While people were opening up the robot and tightening the coupler, the robot would warm up. By the time they put it back together, the problem would have gone away. It had nothing to do with couplers at all.

By the time we had rolled out the coupler "fix" to all robots, the weather had warmed up enough across the country that the issue didn't reoccur. We thought we had fixed it, when actually spring fixed it."

At first they correlated a possible root cause and then after learning from that mistake they finally understood the root cause.

I've seen it happen many times where people with not enough time and knowledge to debug a huge system had to resort to shotgun debugging. IME taking the time to understand always ends up 1) solving the problem and 2) saving time and money.

This is especially true when the problem is actually caused by two or more root causes.