This manual has severe issues.  There is a moldy staining on the outer covers.  Front & Rear.  This manual was defeinitely in a moist environment for a while.  That said, the paper is strong and not brittle, and it might be possible to clean this staining.  I do not know. 

The mold also has stained some of the blank rear pages, saved for notes.  To a lesser extent, there is staining on the actual pages with writing and illustrations, schematics, etc.  I CAN PROVIDE MORE PHOTOS if you'd like. 

Other than this, the "important" pages with diagrams and schematics and text are all good.  The ink is clear and the paper is strong.  The information is very readable so this can still teach the reader a lot.

If there is ANYTHING I can provide for you, let me know.  I will take photos or scans of certain areas of the book if you'd like.  Let me get you the information you need to make an informed decision about bidding on this rare old documentation. 
 

....and thanks for looking.