I need your help. I've got some old, as in over 35 years old, USGI backpacks that need some reconditioning.
These are the US Jungle Rucks with the curved frames that were used in the early Viet Nam war before the ALICE packs came out. I really like these packs because of the curved frames and smaller packs that allow other things like Medic bags or sleeping bags to be lashed to the frames, leaving an over all smaller pack.
The pack I am talking bout is the one on the far left in this photo from our entry in the Winter Bug Out Campout Contest.

The problems I'm having are the nylon straps. They are now very stiff and are very hard to move through the strap buckles. They are putting up one heck of a fight!
Is there any good ways to recondition the nylon straps, making them more flexable and sliding easier through their metal buckles?
I really do not want to replace the nylon straps with new ones because I want to keep these packs as original as possible. I have 3 of these and I would like them as close to 100% functioning as I can get them while remaining original. I still use these for hiking and backpacking.
Thanks in advance for any good advice you may be able to share with me.
Medic73