Hi,
Your Perdy Damascus Grand Rotary was made by National and sold through MW. Here's a Western Electric manual that should help:
http://www.sil.si.edu/DigitalCollect...ges/image8.htm
Takes a 20x1 needle, you can try a 15x1 scooted down. National SM Yahoo group is a good resource.
http://groups.yahoo.com/group/nsmco/
Enjoy your new beauty,
Jon