On the 70 Flexi units I rebuilt, there is a thin washer that rides between the disc opener and the seed boot. It's part # M17520, it's listed as obsolete for the 70, but the 71 part #B29159 is the one I used. Without the washers, the new openers ran together so tight, they'd hardly turn. The parts guys at the local JD dealership were very helpful. You can also go here,
John Deere - Parts Catalog , and find the parts breakdown for a bunch of JD planters. I printed off a complete set of the parts for my 70s, and took it with me to JD when I needed the parts. Many of the parts for my older 70 Flexis we were able to reference to the same part on a 71, and they worked just fine. Good luck with your rebuild. Mark