They need the rod to match the segments; there will be slight variations from rod to rod and they want to get it as close as possible to the original. That's why they want you to ship the whole thing back. Whether it's worth the $ for the repair is up to you. The Sage RPL 906 I bought back in the late 80's has been back to the shop 4 times for busted tips (every one my fault), the last time 2 years ago, 25 years after purchase. I was sure they'd tell me they didn't have any more tips but the guy I talked to on the phone said they keep a pretty decent inventory, even for the older stuff. Couldn't imagine fishing without that rod.
Regards,
Scott
btw, welcome to the forum