If you decide not to replace your loom Kojaycat sell the various plastic block connectors to you can release the existing male or female terminals by pressing down on the tang end, clean them up then re-fit into new unbroken or yellowed blocks.
I sent a photo via their enquiry email to make sure I bought the right block connectors.
On my 400 I bought a new loom from Elextrex World, the colours were correct.
On my 500 I just fitted new block connectors, made up small looms like for the tail lights myself.