Arrived today to replace 4” media filter with lower MERV rating along with replace/reroute 8” return on the kids & bonus room system along with replace/reroute 10” return on master-bedroom closet.Upon arrival removed original duct-work from each system found on the master-bedroom return to have manual damper installed which was causing rattling noise removed damper then re-ran new 8” & 10” flexible duct-run confirming noise issue was resolved