[Milsurplus] Germanium diodes

[Ray Fantini]

Anyone have any ideas about the affects of age on Germanium diodes? starting to suspect that several of the diodes used in the 618S/ ARC-38 family of radios I have been working on are failing to provide sufficient voltage to work properly. they work in discriminator circuits to provide reference voltage to servo amplifiers. The newest ones are from 1959/60 so they are over forty years old and do not know if their internal resistance increased with age? 
Ray Fantini KA3EKH