Re: I have ended up helping the field engineers that are proudly billiing me...
I also recall teaching him how to use the low level tools to perform the diagnostics at both software and hardware layers.
I had a similar situation when Sun released their first Sparc stations in France. Their maintenance engineer knew Sun OS 3 very well, but OS 4 had everything changed, swap place, etc. I had to guide him to find the various configuration files that were no more where they used to be.