The yellow wire may have been added to replace a broken or frayed original wire. The 43V to power the coils is daisy chained, so I don't think it is a modification, just a replacement wire.

The washer should be on all coils, but it does not matter if it is not installed. I think Greg has them - http://www.rtbb.com.au/catalog/product_info.php?products_id=416 - They look the same to me.