dtklunk,
Early Pfaff 335's had only a 4 mm stitch length max. I think yours is 6mm because of the N in the model plate. Send us a pic of the reverse lever and the plate behind it. H3 so 11mm lift of foot, B means a B class which is for lighter material, S for cloth. No M which is safety clutch, no P for 4 motion drop feed. She is dirty. I would go thru and clean it up, check for worn parts and even repaint it.. But that's me.
glenn