Yes - it's often the simplest thing that can render a comlete machine inert, but can often be hard to trace.
You were sharp-eyed enough to see the problem almost immediately but often the whole notion of a simple cause just does not occur to the operator.
Many people - and I have been caught out too - tend to think difficult causes or solutions first. It seems a curious trait of the technical mind, almost worthy of a psychology PhD student's thesis!
I've seen an entire, amateur-engineering project delayed by some two years because every part was made accurately to drawings and no-one had considered the possibility eventually proven by others, of an error on a drawing. Another hold-up was eventually traced, indirectly, after umpteen hours of effort, to a simple pipe-joint gasket missing its hole for the fluid! In both cases, the most experienced people involved had drifted into deep technicalities by being unable to expect some, very simple cause first.
In one case that caught me, the solution was not the complexities of screws and gears but pairs of blocks of wood, as spacers!
I also recall an incident at work where several, very highly-qualified and experienced people had all assumed their item under test had failed... A fresh pair of eyes quickly spotted the real cause: someone had mis-set a test-instrument, revealed merely by the direction of the pointers on two switch-knobs.
So while you were astute enough to see what was wrong very quickly, and that it was a very simple fault; others might well have dismantled and re-assembled the whole engine successfully, and still never identified the original fault they corrected without realising it!
