Bob,
There are several folks on ebay who offer Martin turret manuals in hard copy and scanned CD/DVD format. I've found that for my needs, the CD/DVD versions work really well because you can print them out into a hard copy at any time and and when opened on your computer, you can magnify the images and part numbers. My favorite series of scanned turret manuals right now come from a fellow named Andy Moorer at JamminPower. he scanned 41 turret manuals at 300 to 600 dpi and offers them in a two DVD set for $28.99 plus shipping. There are a number of Martin upper manuals on the DVD both WWII and post WWII I think. Here's the link to his ebay store. What model are you working on?
http://shop.ebay.com/merchant/jamminpowerGood Luck!