You can contact Marlin and get one. The following is from their website (http://www.marlinfirearms.com/FAQs/index.htm#Q02):
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Q) How can I get a product catalog or Owner's Manual?
To obtain a product catalog click here
To obtain an Owner's Manual
Please send your name and address to:
Marlin Services
P.O. Box 248
North Haven, CT 06473
Be sure to specify the model name and serial number of the specific firearms.
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Having purchased some spare parts from them, they seem to like to be contacted by mail. Once they get you letter, their response is pretty prompt.