I have an old cane {South Bend, Model 52), and the guides wraps were replace (guides are the original for silk line). With Cortland's "SYLK" Fly Line, the smaller diameter line fits through the ruby agate stripping guide on the rod.

Guess the rod was retired for about 50 years, and was stored in somebody's closet. Casts as if it is brand new, and I can feel its singing, when casting. Lovely fly rod, but it needed Cortland to come out with a true replacement for silk line.