Here are a nice collection of online manuals for:
HP-41C Handbook Owner’s Handbook and Progamming Guide
HP-41C Quick Reference Quick Reference Guide
HP-41C Card Reader 82104A Card Reader Owner’s Handbook
HP-41C Applications Standard Applications Handbook
HP-41C Wand 82153A Wand Owner’s Manual
HP-41C Time Module 82182A Time Module Owner’s Manual
HP-41C Printer 82143A Printer Owner’s Manual
http://www.greendyk.nl/