Whenever I have an issue with a seat that I have not run into before, this is the book I turn to. I highly recommend it. It is called The Caners Handbook and it is written by Bruce W. Miller and Jim Widess. It has great pictures and step by step instructions. There are also chapters on wicker repair, split oak, pressed cane and swedish cord. It is a wealth of information if you are going to do seat repairs.
It is available in The Greentiques Solution Bookstore, or just click on Rory's Book Of The Week, located on the sidebar.
Repairing these old chairs is a great way to keep them out of landfills and make some money at the same time. Give it a try!