HI my 2215 is making a rattling noise, is this pointing to the impeller needing to be replaced ???

The best way to tell would be to have a look at the impeller
But yes it is likely to be the impeller or an air lock

Check for play in the impeller shaft. It may just need a thorough clean.

I started my new 33L tank today and put in my Eheim 2006 and it was rattley as hell. The filter is rated for tanks around this size and it was the smallest size wise I could find.
I was about to take it back to the shop, and then we noticed that it only makes the noise when in proximity to the glass. Some kind of physics phenomenon! So we have rigged it up on a rock (you will see what i mean when I start my tank log thread) a little way out from the glass and it is almost silent. And I mean that you have to stand right up close and listen to hear it.
So take it away from the glass and see if it's quieter, you might find there's nothing wrong with it
(unless of course it was good and now it's noisey )