Hi there fella, I could be compltely wrong but i was told that the reason for the soft rivets is to let the sprocket centre itself over time, I was also told that even from new the dynamo drive sprockets were never 100% centered and when fitted you ended up with a tight chain with the sprocket half way round a revolution and a slack chain on another half a revolution. I found exactly that problem when I bought a new dynamo chain and sprockets so i give up in the end and bought a longstroke dynamo belt conversion kit from srm. Did make a massive difference in the noise department, a lot less rattlely. All the best, Chicago