I have noticed this weekend that on filling my cylinder, there is a "leak" coming from the small hole in the brass cap on the gauge end of the cylinder. It starts at anything over 100 Bar. It continues to leak almost like a slow puncture, with the gauge slowly losing pressure until it reaches about 70 Bar.I would think that this is an overpressure relief mechanism that is now faulty.
Has anyone come accross this problem before? Maybe its just a seal that needs replacing?