I happen to have a new (less than 100 miles) Shimano 13-28 on my Peugot Triathlon I restored. If the 600 series Derailuer can handle the 28 sprocket, then I can just order a replacement FW for myself and get my friend up and running without the skipping (I am doing this for a friend). Thanks for the reply. It reinforces what I thought I would have to do anyway.