Reddit mentions of Dia-Compe 95 Ferrule, for AGC Brake Levers, 5.0mm ID, Bag of 10

I shall harness the black arts of vintage bike repair to help you. Hope this is applicable to your problem!

• If the housing is just being pulled into the lever body with no sign of stopping, chances are that you are missing a ferrule.
  
• Schwinn Circuits came with early Dia-Compe aero brake levers. REFERENCE.
  
• Yours look like AGC250 ("Aero Gran Compe), but all late-80s Dia-Compe aero levers follow the same layout. REFERENCE.
  
• These levers use a special rounded ferrule to hold the housing against the lever body. Housing ferrules are called "end buttons" in Dia-Compe parlance. If your lever is an Aero Compe it originally had a type 95 end button (second row, first to the left) REFERENCE.
  
  If no ferrule is mounted, which mechanics more familiar with newer brake levers might be inclined to do, the housing will pull into the lever. If a regular brake ferrule is used, the housing will stop, but might pivot a bit around which might lead to fraying.
  
  The original type 95 ferrule can be found here. However, I think you could use any thick brake housing ferrule with 5mm inner diameter if you wish. Check your local bike shops! At my old workshop we would most likely just have put a regular, thick-walled ferrule in a vice and punched it with a rounded dowel or sanded down a stepped ferrule to fabricate one to original spec.
  
  Please post more pics of the lever in question so that I can nail down exactly which model it is and what the ferrule is supposed to look like.