My Tiguan 2.0TDI has an intermittent long crank when starting for the first time of the day or when I return to it after a shift at work so roughly 8-10 hours after it was last driven. It has a new battery as that was my first thought and didn’t cost too much. This fault is intermittent but I would say it happens more than not. When it doesn’t fault the starter turns over fine and the engine starts up perfectly which makes me thing the glow plug system and fuel delivery is ok. When it does fault it does seem like it is a slightly lower cranking speed as to when it’s fine so I am aware that there might not be enough voltage to the fuel pump or glow plug system when it happens. Had a look at the fuse block in the engine bay and I found some rust/corrosion on some of the terminals for the high amp fuses for the alternator in particular. Would this be a good place to start or is there something else that might be more common? Any thoughts would be appreciated!