In other words, not trying to design an obsolete part into a new project, but analysing an existing system to see if the problem is due to the obsolete part.

a most honorable excersize

regardless of whare I put the emphasis in my post i totally agree that for "analysing an existing system" a datasheet for the parts used often come in handy.

My issue was that if these old datasheets were available that might make someone use the old parts in new designs.

Erik