I've got a customer who came in complaining that the clutch pedal had gone 'funny': it wasn't 'coming back up' like it used to. As he was in for service anyway, we replaced the clutch fluid, and it 'seemed ok' afterwards.
He came back a few weeks later saying that he was having problems with the clutch being 'random'. In the morning, the clutch doesn't disengage properly when he fully depresses the pedal (he has to be in neutral to start the car), but after a few miles of driving, it works ok.
He wondered whether it wasn't the difference between the car being 'warmed up or not', so we kept the car overnight to try, but haven't been able to see any problem.
What are we missing?