The five line swivel is modified it has a drilled bold ant nut setup through the center
Wainman will have there fifth line kits soon similar swivel interesting to see the stop setup on that
Failing that the switch kites swivel will work as a replacment

The 4 and 5 line swivels are a little bit different as pedleym stated. Dunno if the 4 line swivel will work as 5 line will have to have a look in the morning.

Pretty sure blue safety/bungee line should connect to 5th line which goes through middle of the swivel.

So the 5th line is a bit different to the other lines and the hole in the center swivel is a lot larger on the 4 line.

What you could try to do is pull the front safety line out through the side of the swivel and use that as the 5th line (leave it running through the middle of the swivel). Then just get a new front line and attach it to the side of the swivel. You might have to check the line length for the 5th line through.

Our 5 line bar is taken apart at the moment so not 100% sure if this will work.