E*Thirteen Front Hub End Caps 15mm....help...

Hi ,
I have a YT Jeffsy Pro that arrived minus an end cap on the front hub so I cannot safely tighten / attach the front wheel...
I am going through a very long and difficult process of trying to get one but it seems they are sold out everywhere and YT are dragging their heels as always ...
Is there an alternative end cap I can use ?
Any ideas would be very greatly appreciated !!!