Hi everyone,
the car in question is a 2002 Passat TDi, with the AVB engine. It's my dads immaculate pride and joy and I noticed yesterday the brake pedal was hard when out checking after a service.
Checked for the usual split vacuum pipes and checked both solenoids were working, and found nothing. No fault codes present either. There is a little vacuum in the turbo system but not much.
Removed the vacuum pipe where it enters the brake servo and there's plenty of vacuum present. I noticed when the system is connected up as normal, there's very little vacuum at the take off point on the main vac line from the pump (the little outlet that supplies vacuum to the turbo/egr system). Then magically it started working as normal again.

Am I looking at a servo that's on its way out? I checked the drains for crap and leaves and, while there was no water lying there, you can see staining as if water is not draining away quick enough.
Any ideas appreciated