How do you soften a stiff fabric cord with dried out rubber insulation?

[Telephones_etc]

Hello fellow CRPF'ers. As you may (or may not) know, I recently purchased a 1937 WE 302 and I've been restoring and cleaning it. I just finished re-attaching the handset cord to the handset, but I've run into a few problems with the cord itself. It's quite stiff and the rubber insulation within is hard and brittle. I read a 2015 post by TelePlay about his endeavors to soften one of his cords...

http://www.classicrotaryphones.com/forum/index.php?topic=13912

...and it helps a little. However, in his post the internal wires had fabric covering, not rubber. I've dealt with pretty hard cords before, and I've always found that soaking them in hot/warm water, then hanging them on a weight to dry seems to do the trick. However, this cord is very stiff and I'm not entirely sure it'll work this time. It almost seems that the insulation melted at some point, as it is 'locked' into position. Does anyone have insight into this issue?

Thanks,
Telephones_etc

[Key2871]

You would be better off finding a replacement cord. There really is no way to repair the wires internal of the cord.
Rubber just dries out after a while and replacing it is your best bet. It's only a matter of time before it shorts conductor's and will fail anyway.

[AL_as_needed]

Check out oldphoneworks.com , they have a nice selection of new and NOS cords both cloth and rubber.

[TelePlay]

     Regular Member Post

I just finished re-attaching the handset cord to the handset, but I've run into a few problems with the cord itself. It's quite stiff and the rubber insulation within is hard and brittle. I read a 2015 post by TelePlay about his endeavors to soften one of his cords...

http://www.classicrotaryphones.com/forum/index.php?topic=13912

That topic I created was for softening cloth covered conductors inside of a cloth outer sheathing. It will not work for a cloth covered cord with rubber coated internal conductors.

I've tried to soften rubber cords, with some success, but rejuvenating, putting the correct or similar plasticizers back into old, stiff rubber is quite difficult and may be impossible, especially if the rubber is inside of a cloth sheathing.

Once that rubber coating turns brittle (stiff), it just crumbles when flexed. As suggested, a replacement cord is the best fix.