How do you clean up the silver bit of this? Mine has lost its colour

Hi, thank you for your enquiry.

To restore colour you can try to use a fine wire wool and swirling it in small circles whilst applying a little pressure and metal polish should improve the finish. If your fireplace insert has been subject to moisture or dirt from general use, you can attempt to clear it off with WD40 on a duster, this should help to remove the tarnishing.