NOS Pomona Cables, gassing+split plastic how to clean?

[Vertamps]

Hello, bought these two vintage shielded Pomona cables(model 1167-60).
 There probably from the early 80's im guessing, Well i got an extra discount as each cable has a connector end that is split. Just gonna plastic epoxy them.
The cables are gassing and SMELL, and leave the smell on my hands.

*Will Soaking in isopropyl alcohol damage the cables further and cause more gassing?
-Cleaning a few times with dish soap and water seems safe option.
 
Alternative @$55 brand new from digikey, with the extra discount from the seller i figured i could save the cables and be happy.
/*edit,  a quick google mentions baking soda scrub, ill try that on one cable and dish soap on the second cable then compare.*/

[stj]

if the cables are losing the plsticiser then they will become stiff and crack

[Stray Electron]

  I'm not sure about the plastic used to make those cables but for rubber and synthetic rubber products they say NOT to use hydrocarbon solvents to clean them.  They recommend ammonia for cleaning.  Solvents dissolve out the plasticizers and make plastic and rubber products to dry out and to crack even worse.

  I have some very old Pomona cables and I don't think that I've ever seen any of the plastic crack but perhaps Pomona changed the formulation at some point.

   I just use plain household ammonia from the grocery store for cleaning. I usually dilute it with about equal parts water but for heavy duty cleaning I just use it straight. 

[Vertamps]

Ill try the ammonia, the cables are operating fine and i think total for $35 for the pair after discount the may work till the world stops turning.