I have a different machine, but also get the rattle when the bobbin is low. It's a good low bobbin indicator, so I know not to start a pattern where a start/stop would be difficult to hide. However, I use the bobbin until it runs out. I've always heard that it's better to wind the bobbin tighter rather than looser. Don't know if it's actually for better machine performance or it's so you get more thread on the bobbin.
I also use ebay bobbins. I got 100. A couple were not balanced so I pitched them.